diff --git a/Cargo.lock b/Cargo.lock
index 7f29e76..8d85269 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -55,15 +57,15 @@ checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
 
 [[package]]
 name = "bitflags"
-version = "1.2.1"
+version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bumpalo"
-version = "3.7.0"
+version = "3.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c59e7af012c713f529e7a3ee57ce9b31ddd858d4b512923602f74608b009631"
+checksum = "d9df67f7bf9ef8498769f994239c45613ef0c5899415fb58e9add412d2c1a538"
 
 [[package]]
 name = "byteorder"
@@ -73,15 +75,15 @@ checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 
 [[package]]
 name = "bytes"
-version = "1.0.1"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b700ce4376041dcd0a327fd0097c41095743c4c8af8887265942faf1100bd040"
+checksum = "c4872d67bab6358e59559027aa3b9157c53d9358c51423c17554809a8858e0f8"
 
 [[package]]
 name = "cc"
-version = "1.0.68"
+version = "1.0.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4a72c244c1ff497a746a7e1fb3d14bd08420ecda70c8f25c7112f2781652d787"
+checksum = "d26a6ce4b6a484fa3edb70f7efa6fc430fd2b87285fe8b84304fd0936faa0dc0"
 
 [[package]]
 name = "cfg-if"
@@ -215,9 +217,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-deque"
-version = "0.8.0"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94af6efb46fef72616855b036a624cf27ba656ffc9be1b9a3c931cfc7749a9a9"
+checksum = "6455c0ca19f0d2fbf751b908d5c55c1f5cbc65e03c4225427254b46890bdde1e"
 dependencies = [
  "cfg-if",
  "crossbeam-epoch",
@@ -286,13 +288,14 @@ dependencies = [
 
 [[package]]
 name = "derive_more"
-version = "0.99.14"
+version = "0.99.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5cc7b9cef1e351660e5443924e4f43ab25fbbed3e9a5f052df3677deb4d6b320"
+checksum = "40eebddd2156ce1bb37b20bbe5151340a31828b1f2d22ba4141f3531710e38df"
 dependencies = [
  "convert_case",
  "proc-macro2",
  "quote",
+ "rustc_version 0.3.3",
  "syn",
 ]
 
@@ -369,42 +372,42 @@ dependencies = [
 
 [[package]]
 name = "futures-channel"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e682a68b29a882df0545c143dc3646daefe80ba479bcdede94d5a703de2871e2"
+checksum = "5da6ba8c3bb3c165d3c7319fc1cc8304facf1fb8db99c5de877183c08a273888"
 dependencies = [
  "futures-core",
 ]
 
 [[package]]
 name = "futures-core"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0402f765d8a89a26043b889b26ce3c4679d268fa6bb22cd7c6aad98340e179d1"
+checksum = "88d1c26957f23603395cd326b0ffe64124b818f4449552f960d815cfba83a53d"
 
 [[package]]
 name = "futures-io"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "acc499defb3b348f8d8f3f66415835a9131856ff7714bf10dadfc4ec4bdb29a1"
+checksum = "522de2a0fe3e380f1bc577ba0474108faf3f6b18321dbf60b3b9c39a75073377"
 
 [[package]]
 name = "futures-sink"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a57bead0ceff0d6dde8f465ecd96c9338121bb7717d3e7b108059531870c4282"
+checksum = "36ea153c13024fe480590b3e3d4cad89a0cfacecc24577b68f86c6ced9c2bc11"
 
 [[package]]
 name = "futures-task"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a16bef9fc1a4dddb5bee51c989e3fbba26569cbb0e31f5b303c184e3dd33dae"
+checksum = "1d3d00f4eddb73e498a54394f228cd55853bdf059259e8e7bc6e69d408892e99"
 
 [[package]]
 name = "futures-util"
-version = "0.3.15"
+version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "feb5c238d27e2bf94ffdfd27b2c29e3df4a68c4193bb6427384259e2bf191967"
+checksum = "36568465210a3a6ee45e1f165136d68671471a501e632e9a98d96872222b5481"
 dependencies = [
  "autocfg",
  "futures-core",
@@ -449,9 +452,9 @@ dependencies = [
 
 [[package]]
 name = "h2"
-version = "0.3.3"
+version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "825343c4eef0b63f541f8903f395dc5beb362a979b5799a84062527ef1e37726"
+checksum = "d7f3675cfef6a30c8031cf9e6493ebdc3bb3272a3fea3923c4210d1830e6a472"
 dependencies = [
  "bytes",
  "fnv",
@@ -506,9 +509,9 @@ dependencies = [
 
 [[package]]
 name = "http"
-version = "0.2.4"
+version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "527e8c9ac747e28542699a951517aa9a6945af506cd1f2e1b53a576c17b6cc11"
+checksum = "1323096b05d41827dadeaee54c9981958c0f94e670bc94ed80037d1a7b8b186b"
 dependencies = [
  "bytes",
  "fnv",
@@ -517,9 +520,9 @@ dependencies = [
 
 [[package]]
 name = "http-body"
-version = "0.4.2"
+version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60daa14be0e0786db0f03a9e57cb404c9d756eed2b6c62b9ea98ec5743ec75a9"
+checksum = "399c583b2979440c60be0821a6199eca73bc3c8dcd9d070d75ac726e2c6186e5"
 dependencies = [
  "bytes",
  "http",
@@ -528,9 +531,9 @@ dependencies = [
 
 [[package]]
 name = "httparse"
-version = "1.4.1"
+version = "1.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f3a87b616e37e93c22fb19bcd386f02f3af5ea98a25670ad0fce773de23c5e68"
+checksum = "acd94fdbe1d4ff688b67b04eee2e17bd50995534a61539e45adfefb45e5e5503"
 
 [[package]]
 name = "httpdate"
@@ -540,9 +543,9 @@ checksum = "6456b8a6c8f33fee7d958fcd1b60d55b11940a79e63ae87013e6d22e26034440"
 
 [[package]]
 name = "hyper"
-version = "0.14.9"
+version = "0.14.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07d6baa1b441335f3ce5098ac421fb6547c46dda735ca1bc6d0153c838f9dd83"
+checksum = "15d1cfb9e4f68655fa04c01f59edb405b6074a0f7118ea881e5026e4a1cd8593"
 dependencies = [
  "bytes",
  "futures-channel",
@@ -604,15 +607,15 @@ checksum = "68f2d64f2edebec4ce84ad108148e67e1064789bee435edc5b60ad398714a3a9"
 
 [[package]]
 name = "itoa"
-version = "0.4.7"
+version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd25036021b0de88a0aff6b850051563c6516d0bf53f8638938edbb9de732736"
+checksum = "b71991ff56294aa922b450139ee08b3bfc70982c6b2c7562771375cf73542dd4"
 
 [[package]]
 name = "js-sys"
-version = "0.3.51"
+version = "0.3.55"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83bdfbace3a0e81a4253f73b49e960b053e396a11012cbd49b9b74d6a2b67062"
+checksum = "7cc9ffccd38c451a86bf13657df244e9c3f37493cce8e5e21e940963777acc84"
 dependencies = [
  "wasm-bindgen",
 ]
@@ -637,9 +640,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.97"
+version = "0.2.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "12b8adadd720df158f4d70dfe7ccc6adb0472d7c55ca83445f6a5ab3e36f8fb6"
+checksum = "a2a5ac8f984bfcf3a823267e5fde638acc3325f6496633a5da6bb6eb2171e103"
 
 [[package]]
 name = "log"
@@ -672,9 +675,9 @@ dependencies = [
 
 [[package]]
 name = "matches"
-version = "0.1.8"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ffc5c5338469d4d3ea17d269fa8ea3512ad247247c30bd2df69e68309ed0a08"
+checksum = "a3e378b66a060d48947b590737b30a1be76706c8dd7b8ba0f2fe3989c68a853f"
 
 [[package]]
 name = "md5"
@@ -684,9 +687,9 @@ checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"
 
 [[package]]
 name = "memchr"
-version = "2.4.0"
+version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b16bd47d9e329435e309c58469fe0791c2d0d1ba96ec0954152a5ae2b04387dc"
+checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
 
 [[package]]
 name = "memoffset"
@@ -727,9 +730,9 @@ dependencies = [
 
 [[package]]
 name = "native-tls"
-version = "0.2.7"
+version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8d96b2e1c8da3957d58100b09f102c6d9cfdfced01b7ec5a8974044bb09dbd4"
+checksum = "48ba9f7719b5a0f42f338907614285fb5fd70e53858141f69898a1fb7203b24d"
 dependencies = [
  "lazy_static",
  "libc",
@@ -801,9 +804,9 @@ checksum = "692fcb63b64b1758029e0a96ee63e049ce8c5948587f2f7208df04625e5f6b56"
 
 [[package]]
 name = "openssl"
-version = "0.10.35"
+version = "0.10.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "549430950c79ae24e6d02e0b7404534ecf311d94cc9f861e9e4020187d13d885"
+checksum = "8d9facdb76fec0b73c406f125d44d86fdad818d66fef0531eec9233ca425ff4a"
 dependencies = [
  "bitflags",
  "cfg-if",
@@ -821,9 +824,9 @@ checksum = "28988d872ab76095a6e6ac88d99b54fd267702734fd7ffe610ca27f533ddb95a"
 
 [[package]]
 name = "openssl-sys"
-version = "0.9.65"
+version = "0.9.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a7907e3bfa08bb85105209cdfcb6c63d109f8f6c1ed6ca318fff5c1853fbc1d"
+checksum = "69df2d8dfc6ce3aaf44b40dec6f487d5a886516cf6879c49e98e0710f310a058"
 dependencies = [
  "autocfg",
  "cc",
@@ -844,6 +847,15 @@ version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d4fd5641d01c8f18a23da7b6fe29298ff4b55afcccdf78973b24cf3175fee32e"
 
+[[package]]
+name = "pest"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10f4872ae94d7b90ae48754df22fd42ad52ce740b8f370b03da4835417403e53"
+dependencies = [
+ "ucd-trie",
+]
+
 [[package]]
 name = "phf"
 version = "0.8.0"
@@ -960,9 +972,9 @@ checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.27"
+version = "1.0.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0d8caf72986c1a598726adc988bb5984792ef84f5ee5aa50209145ee8077038"
+checksum = "b9f5105d4fdaab20335ca9565e106a5d9b82b6219b5ba735731124ac6711d23d"
 dependencies = [
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 ]
@@ -1079,9 +1091,9 @@ dependencies = [
 
 [[package]]
 name = "redox_syscall"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ab49abadf3f9e1c4bc499e8845e152ad87d2ad2d30371841171169e9d75feee"
+checksum = "8383f39639269cde97d255a32bdb68c047337295414940c68bdd30c2e13203ff"
 dependencies = [
  "bitflags",
 ]
@@ -1155,7 +1167,16 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 dependencies = [
- "semver",
+ "semver 0.9.0",
+]
+
+[[package]]
+name = "rustc_version"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0dfe2087c51c460008730de8b57e6a320782fbfb312e1f4d520e6c6fae155ee"
+dependencies = [
+ "semver 0.11.0",
 ]
 
 [[package]]
@@ -1182,9 +1203,9 @@ checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
 [[package]]
 name = "security-framework"
-version = "2.3.1"
+version = "2.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "23a2ac85147a3a11d77ecf1bc7166ec0b92febfa4461c37944e180f319ece467"
+checksum = "525bc1abfda2e1998d152c45cf13e696f76d0a4972310b22fac1658b05df7c87"
 dependencies = [
  "bitflags",
  "core-foundation",
@@ -1195,9 +1216,9 @@ dependencies = [
 
 [[package]]
 name = "security-framework-sys"
-version = "2.3.0"
+version = "2.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e4effb91b4b8b6fb7732e670b6cee160278ff8e6bf485c7805d9e319d76e284"
+checksum = "a9dd14d83160b528b7bfd66439110573efcfbe281b17fc2ca9f39f550d619c7e"
 dependencies = [
  "core-foundation-sys",
  "libc",
@@ -1229,7 +1250,16 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 dependencies = [
- "semver-parser",
+ "semver-parser 0.7.0",
+]
+
+[[package]]
+name = "semver"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f301af10236f6df4160f7c3f04eec6dbc70ace82d23326abad5edee88801c6b6"
+dependencies = [
+ "semver-parser 0.10.2",
 ]
 
 [[package]]
@@ -1239,19 +1269,28 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
 [[package]]
-name = "serde"
-version = "1.0.126"
+name = "semver-parser"
+version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec7505abeacaec74ae4778d9d9328fe5a5d04253220a85c4ee022239fc996d03"
+checksum = "00b0bef5b7f9e0df16536d3961cfb6e84331c065b4066afb39768d0e319411f7"
+dependencies = [
+ "pest",
+]
+
+[[package]]
+name = "serde"
+version = "1.0.130"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f12d06de37cf59146fbdecab66aa99f9fe4f78722e3607577a5375d66bd0c913"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.126"
+version = "1.0.130"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "963a7dbc9895aeac7ac90e74f34a5d5261828f79df35cbed41e10189d3804d43"
+checksum = "d7bc1a1ab1961464eae040d96713baa5a724a8152c1222492465b54322ec508b"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1260,9 +1299,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.64"
+version = "1.0.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "799e97dc9fdae36a5c8b8f2cae9ce2ee9fdce2058c57a93e6099d919fd982f79"
+checksum = "0f690853975602e1bfe1ccbf50504d67174e3bcf340f23b5ea9992e0587a52d8"
 dependencies = [
  "itoa",
  "ryu",
@@ -1299,15 +1338,15 @@ checksum = "2579985fda508104f7587689507983eadd6a6e84dd35d6d115361f530916fa0d"
 
 [[package]]
 name = "siphasher"
-version = "0.3.5"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cbce6d4507c7e4a3962091436e56e95290cb71fa302d0d270e32130b75fbff27"
+checksum = "533494a8f9b724d33625ab53c6c4800f7cc445895924a8ef649222dcb76e938b"
 
 [[package]]
 name = "slab"
-version = "0.4.3"
+version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f173ac3d1a7e3b28003f40de0b5ce7fe2710f9b9dc3fc38664cebee46b3b6527"
+checksum = "c307a32c1c5c437f38c7fd45d753050587732ba8628319fbdf12a7e289ccc590"
 
 [[package]]
 name = "smallvec"
@@ -1317,9 +1356,9 @@ checksum = "fe0f37c9e8f3c5a4a66ad655a93c74daac4ad00c441533bf5c6e7990bb42604e"
 
 [[package]]
 name = "socket2"
-version = "0.4.0"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e3dfc207c526015c632472a77be09cf1b6e46866581aecae5cc38fb4235dea2"
+checksum = "5dc90fe6c7be1a323296982db1836d1ea9e47b6839496dde9a541bc496df3516"
 dependencies = [
  "libc",
  "winapi",
@@ -1347,7 +1386,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d022496b16281348b52d0e30ae99e01a73d737b2f45d38fed4edf79f9325a1d5"
 dependencies = [
  "discard",
- "rustc_version",
+ "rustc_version 0.2.3",
  "stdweb-derive",
  "stdweb-internal-macros",
  "stdweb-internal-runtime",
@@ -1446,9 +1485,9 @@ dependencies = [
 
 [[package]]
 name = "subprocess"
-version = "0.2.7"
+version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "334b801f9ca2529ba9605109f1d2835f15aff94cd6cfe5afe6ce8cf71e5fd3c4"
+checksum = "055cf3ebc2981ad8f0a5a17ef6652f652d87831f79fddcba2ac57bcb9a0aa407"
 dependencies = [
  "libc",
  "winapi",
@@ -1484,9 +1523,9 @@ checksum = "a7973cce6668464ea31f176d85b13c7ab3bba2cb3b77a2ed26abd7801688010a"
 
 [[package]]
 name = "syn"
-version = "1.0.73"
+version = "1.0.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f71489ff30030d2ae598524f61326b902466f72a0fb1a8564c001cc63425bcc7"
+checksum = "c6f107db402c2c2055242dbf4d2af0e69197202e9faacbef9571bbe47f5a1b84"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1596,9 +1635,9 @@ dependencies = [
 
 [[package]]
 name = "tinyvec"
-version = "1.2.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b5220f05bb7de7f3f53c7c065e1199b3172696fe2db9f9c4d8ad9b4ee74c342"
+checksum = "5241dd6f21443a3606b432718b166d3cedc962fd4b8bea54a8bc7f514ebda986"
 dependencies = [
  "tinyvec_macros",
 ]
@@ -1611,9 +1650,9 @@ checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
 
 [[package]]
 name = "tokio"
-version = "1.8.1"
+version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "98c8b05dc14c75ea83d63dd391100353789f5f24b8b3866542a5e85c8be8e985"
+checksum = "c2c2416fdedca8443ae44b4527de1ea633af61d8f7169ffa6e72c5b53d24efcc"
 dependencies = [
  "autocfg",
  "bytes",
@@ -1637,9 +1676,9 @@ dependencies = [
 
 [[package]]
 name = "tokio-util"
-version = "0.6.7"
+version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1caa0b0c8d94a049db56b5acf8cba99dc0623aab1b26d5b5f5e2d945846b3592"
+checksum = "08d3725d3efa29485e87311c5b699de63cde14b00ed4d256b8318aa30ca452cd"
 dependencies = [
  "bytes",
  "futures-core",
@@ -1657,9 +1696,9 @@ checksum = "360dfd1d6d30e05fda32ace2c8c70e9c0a9da713275777f5a4dbb8a1893930c6"
 
 [[package]]
 name = "tracing"
-version = "0.1.26"
+version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09adeb8c97449311ccd28a427f96fb563e7fd31aabf994189879d9da2394b89d"
+checksum = "84f96e095c0c82419687c20ddf5cb3eadb61f4e1405923c9dc8e53a1adacbda8"
 dependencies = [
  "cfg-if",
  "pin-project-lite",
@@ -1668,9 +1707,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-core"
-version = "0.1.18"
+version = "0.1.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9ff14f98b1a4b289c6248a023c1c2fa1491062964e9fed67ab29c4e4da4a052"
+checksum = "46125608c26121c81b0c6d693eab5a420e416da7e43c426d2e8f7df8da8a3acf"
 dependencies = [
  "lazy_static",
 ]
@@ -1682,13 +1721,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59547bce71d9c38b83d9c0e92b6066c4253371f15005def0c30d9657f50c7642"
 
 [[package]]
-name = "unicode-bidi"
-version = "0.3.5"
+name = "ucd-trie"
+version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eeb8be209bb1c96b7c177c7420d26e04eccacb0eeae6b980e35fcb74678107e0"
-dependencies = [
- "matches",
-]
+checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
+
+[[package]]
+name = "unicode-bidi"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "246f4c42e67e7a4e3c6106ff716a5d067d4132a642840b242e357e468a2a0085"
 
 [[package]]
 name = "unicode-normalization"
@@ -1707,9 +1749,9 @@ checksum = "8895849a949e7845e06bd6dc1aa51731a103c42707010a5b591c0038fb73385b"
 
 [[package]]
 name = "unicode-width"
-version = "0.1.8"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
+checksum = "3ed742d4ea2bd1176e236172c8429aaf54486e7ac098db29ffe6529e0ce50973"
 
 [[package]]
 name = "unicode-xid"
@@ -1777,9 +1819,9 @@ checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.74"
+version = "0.2.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d54ee1d4ed486f78874278e63e4069fc1ab9f6a18ca492076ffb90c5eb2997fd"
+checksum = "632f73e236b219150ea279196e54e610f5dbafa5d61786303d4da54f84e47fce"
 dependencies = [
  "cfg-if",
  "serde",
@@ -1789,9 +1831,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-backend"
-version = "0.2.74"
+version = "0.2.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b33f6a0694ccfea53d94db8b2ed1c3a8a4c86dd936b13b9f0a15ec4a451b900"
+checksum = "a317bf8f9fba2476b4b2c85ef4c4af8ff39c3c7f0cdfeed4f82c34a880aa837b"
 dependencies = [
  "bumpalo",
  "lazy_static",
@@ -1804,9 +1846,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-futures"
-version = "0.4.24"
+version = "0.4.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5fba7978c679d53ce2d0ac80c8c175840feb849a161664365d1287b41f2e67f1"
+checksum = "8e8d7523cb1f2a4c96c1317ca690031b714a51cc14e05f712446691f413f5d39"
 dependencies = [
  "cfg-if",
  "js-sys",
@@ -1816,9 +1858,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.74"
+version = "0.2.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "088169ca61430fe1e58b8096c24975251700e7b1f6fd91cc9d59b04fb9b18bd4"
+checksum = "d56146e7c495528bf6587663bea13a8eb588d39b36b679d83972e1a2dbbdacf9"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -1826,9 +1868,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.74"
+version = "0.2.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "be2241542ff3d9f241f5e2cb6dd09b37efe786df8851c54957683a49f0987a97"
+checksum = "7803e0eea25835f8abdc585cd3021b3deb11543c6fe226dcd30b228857c5c5ab"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1839,15 +1881,15 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.74"
+version = "0.2.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d7cff876b8f18eed75a66cf49b65e7f967cb354a7aa16003fb55dbfd25b44b4f"
+checksum = "0237232789cf037d5480773fe568aac745bfe2afbc11a863e97901780a6b47cc"
 
 [[package]]
 name = "web-sys"
-version = "0.3.51"
+version = "0.3.55"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e828417b379f3df7111d3a2a9e5753706cae29c41f7c4029ee9fd77f3e09e582"
+checksum = "38eb105f1c59d9eaa6b5cdc92b859d85b926e82cb2e0945cd0c9259faa6fe9fb"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
diff --git a/README.md b/README.md
index 6f98413..d7731a3 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,8 @@ your disk.
 |---|---|
 |`-h, --help`|Displays help information|
 |`-v, --verbose`|Activate Verbose output|
-|`-d, --depth`|Specify the level of depth to go to when visiting the website|
+|`-d, --depth`|Specify the level of depth to go to when visiting the website. Default is -1 (infinity)|
+|`--ext-depth`|Specify the level of depth to go to when visiting websites that have a different domain name. Default is 0 (ignore external links), -1 is infinity|
 |`-j, --jobs`|Number of threads to use|
 |`-o, --output`|Output directory where the downloaded files are written|
 |`-t, --tries`|Number of times to retry when the downloading of a page fails|
diff --git a/src/args.rs b/src/args.rs
index b7bc1b0..c8be299 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -33,10 +33,17 @@ pub struct Args {
         short,
         long,
         default_value = "-1",
-        help = "Maximum recursion depth to reach when visiting. -1 is the default and will go as far as it can"
+        help = "Maximum recursion depth to reach when visiting. Default is -1 (infinity)"
     )]
     pub depth: i32,
 
+    #[structopt(
+        long,
+        default_value = "0",
+        help = "Maximum recursion depth to reach when visiting external domains. Default is 0. -1 means infinity"
+    )]
+    pub ext_depth: i32,
+
     ///Number of retries when downloading a page fails
     #[structopt(
         short,
@@ -81,21 +88,21 @@ pub struct Args {
 
     /// Regex filter to limit saving pages to only matched ones
     #[structopt(
-        short,
-        long,
-        default_value = ".*",
-        parse(try_from_str = parse_regex),
-        help = "Regex filter to limit to only saving pages that match this expression"
+    short,
+    long,
+    default_value = ".*",
+    parse(try_from_str = parse_regex),
+    help = "Regex filter to limit to only saving pages that match this expression"
     )]
     pub include: Regex,
 
     /// Regex filter to limit saving pages to only matched ones
     #[structopt(
-        short,
-        long,
-        default_value = "$^",
-        parse(try_from_str = parse_regex),
-        help = "Regex filter to exclude saving pages that match this expression"
+    short,
+    long,
+    default_value = "$^",
+    parse(try_from_str = parse_regex),
+    help = "Regex filter to exclude saving pages that match this expression"
     )]
     pub exclude: Regex,
 
diff --git a/src/disk.rs b/src/disk.rs
index a944839..39c6846 100644
--- a/src/disk.rs
+++ b/src/disk.rs
@@ -1,6 +1,7 @@
 use std::fs;
 use std::io::Write;
 use std::path::PathBuf;
+
 use symlink::symlink_auto;
 
 use crate::{error, warn};
diff --git a/src/downloader.rs b/src/downloader.rs
index 09c9f66..1496f56 100644
--- a/src/downloader.rs
+++ b/src/downloader.rs
@@ -1,4 +1,3 @@
-use super::response::{Response, ResponseData};
 use std::collections::HashMap;
 
 use lazy_static::lazy_static;
@@ -7,6 +6,8 @@ use url::Url;
 
 use crate::warn;
 
+use super::response::{Response, ResponseData};
+
 const AUTH_CHUNK_SIZE: usize = 3;
 
 ///A Downloader to download web content
@@ -190,14 +191,14 @@ mod tests {
         assert_eq!(
             parse_auth(
                 &["".to_string(), "pw".to_string()],
-                &Url::parse("https://example.com/").unwrap()
+                &Url::parse("https://example.com/").unwrap(),
             ),
             Err("Invalid arguments supplied to auth".to_string())
         );
         assert_eq!(
             parse_auth(
                 &["username".to_string()],
-                &Url::parse("https://example.com/").unwrap()
+                &Url::parse("https://example.com/").unwrap(),
             ),
             Ok(("username".to_string(), None, "example.com".to_string()))
         );
@@ -209,7 +210,7 @@ mod tests {
                     "h".to_string(),
                     "t".to_string()
                 ],
-                &Url::parse("https://example.com/").unwrap()
+                &Url::parse("https://example.com/").unwrap(),
             ),
             Ok(("un".to_string(), Some("pw".to_string()), "h".to_string()))
         )
diff --git a/src/scraper.rs b/src/scraper.rs
index b13d8cb..46488fd 100644
--- a/src/scraper.rs
+++ b/src/scraper.rs
@@ -1,3 +1,10 @@
+use std::borrow::Borrow;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::path::Path;
+use std::sync::Mutex;
+use std::time;
+
 use crossbeam::channel::{Receiver, Sender, TryRecvError};
 use crossbeam::thread;
 use encoding_rs::Encoding;
@@ -7,12 +14,7 @@ use rand::Rng;
 use regex::Regex;
 use url::Url;
 
-use std::borrow::Borrow;
-use std::collections::HashMap;
-use std::collections::HashSet;
-use std::path::Path;
-use std::sync::Mutex;
-use std::time;
+use crate::{error, info, warn};
 
 use super::args;
 use super::disk;
@@ -21,8 +23,6 @@ use super::downloader;
 use super::response;
 use super::url_helper;
 
-use crate::{error, info, warn};
-
 /// Maximum number of empty recv() from the channel
 static MAX_EMPTY_RECEIVES: usize = 10;
 
@@ -37,8 +37,8 @@ static SLEEP_DURATION: time::Duration = time::Duration::from_millis(SLEEP_MILLIS
 /// adds more as new URLs are found
 pub struct Scraper {
     args: args::Args,
-    transmitter: Sender<(Url, i32)>,
-    receiver: Receiver<(Url, i32)>,
+    transmitter: Sender<(Url, i32, i32)>,
+    receiver: Receiver<(Url, i32, i32)>,
     downloader: downloader::Downloader,
     visited_urls: Mutex<HashSet<String>>,
     path_map: Mutex<HashMap<String, String>>,
@@ -77,8 +77,8 @@ impl Scraper {
     }
 
     /// Push a new URL into the channel
-    fn push(transmitter: &Sender<(Url, i32)>, url: Url, depth: i32) {
-        if let Err(e) = transmitter.send((url, depth)) {
+    fn push(transmitter: &Sender<(Url, i32, i32)>, url: Url, depth: i32, ext_depth: i32) {
+        if let Err(e) = transmitter.send((url, depth, ext_depth)) {
             error!("Couldn't push to channel ! {}", e);
         }
     }
@@ -140,9 +140,10 @@ impl Scraper {
     /// Proces an html file: add new url to the chanel and prepare for offline navigation
     fn handle_html(
         scraper: &Scraper,
-        transmitter: &Sender<(Url, i32)>,
+        transmitter: &Sender<(Url, i32, i32)>,
         url: &Url,
         depth: i32,
+        ext_depth: i32,
         data: &[u8],
         http_charset: Option<String>,
     ) -> Vec<u8> {
@@ -182,16 +183,32 @@ impl Scraper {
 
         dom.find_urls_as_strings()
             .into_iter()
-            .filter(|candidate| Scraper::should_visit(candidate, &url))
+            .filter(|candidate| Scraper::should_visit(candidate))
             .for_each(|next_url| {
-                let mut next_full_url = url.join(&next_url).unwrap();
+                let url_to_parse = Scraper::normalize_url(next_url.clone());
+
+                let mut next_full_url = match url.join(url_to_parse.as_str()) {
+                    Ok(url) => url,
+                    Err(e) => panic!("Failed to parse url: {} | Error: {}", next_url, e),
+                };
+
                 next_full_url.set_fragment(None);
                 let path = url_helper::to_path(&next_full_url);
 
-                if scraper.map_url_path(&next_full_url, path.clone())
-                    && (scraper.args.depth == INFINITE_DEPTH || depth < scraper.args.depth)
-                {
-                    Scraper::push(transmitter, next_full_url, depth + 1);
+                if scraper.map_url_path(&next_full_url, path.clone()) {
+                    if !Scraper::is_on_another_domain(&next_url, &url) {
+                        // If we are determining for a local domain
+                        if scraper.args.depth == INFINITE_DEPTH || depth < scraper.args.depth {
+                            Scraper::push(transmitter, next_full_url, depth + 1, ext_depth);
+                        }
+                    } else {
+                        // If we are determining for an external domain
+                        if scraper.args.ext_depth == INFINITE_DEPTH
+                            || ext_depth < scraper.args.ext_depth
+                        {
+                            Scraper::push(transmitter, next_full_url, depth, ext_depth + 1);
+                        }
+                    }
                 }
 
                 scraper.fix_domtree(next_url, &source_path, &path);
@@ -207,7 +224,13 @@ impl Scraper {
     }
 
     /// Process a single URL
-    fn handle_url(scraper: &Scraper, transmitter: &Sender<(Url, i32)>, url: Url, depth: i32) {
+    fn handle_url(
+        scraper: &Scraper,
+        transmitter: &Sender<(Url, i32, i32)>,
+        url: Url,
+        depth: i32,
+        ext_depth: i32,
+    ) {
         match scraper.downloader.get(&url) {
             Ok(response) => {
                 let data = match response.data {
@@ -216,6 +239,7 @@ impl Scraper {
                         transmitter,
                         &url,
                         depth,
+                        ext_depth,
                         &data,
                         response.charset,
                     ),
@@ -263,7 +287,7 @@ impl Scraper {
     pub fn run(&mut self) {
         /* Push the origin URL and depth (0) through the channel */
         self.map_url_path(&self.args.origin, url_helper::to_path(&self.args.origin));
-        Scraper::push(&self.transmitter, self.args.origin.clone(), 0);
+        Scraper::push(&self.transmitter, self.args.origin.clone(), 0, 0);
 
         thread::scope(|thread_scope| {
             for _ in 0..self.args.jobs {
@@ -285,9 +309,9 @@ impl Scraper {
                                 }
                                 TryRecvError::Disconnected => panic!("{}", e),
                             },
-                            Ok((url, depth)) => {
+                            Ok((url, depth, ext_depth)) => {
                                 counter = 0;
-                                Scraper::handle_url(&self_clone, &tx, url, depth);
+                                Scraper::handle_url(&self_clone, &tx, url, depth, ext_depth);
                                 self_clone.sleep(&mut rng);
                             }
                         }
@@ -313,14 +337,14 @@ impl Scraper {
         std::thread::sleep(delay_duration);
     }
 
-    /// If a URL should be visited, or does it belong to another domain
-    fn should_visit(url: &str, base: &Url) -> bool {
+    /// If a URL should be visited (ignores `mail:`, `javascript:` and other pseudo-links)
+    fn should_visit(url: &str) -> bool {
         match Url::parse(url) {
             /* The given candidate is a valid URL, and not a relative path to
-             * the next one. Therefore, we have to check if this URL belongs
-             * to the same domain as our current URL. If the candidate has the
-             * same domain as our base, then we should visit it */
-            Ok(not_ok) => not_ok.domain() == base.domain(),
+             * the next one. Therefore, we have to check if this URL is valid.
+             * If it is, we should visit it.
+             */
+            Ok(not_ok) => not_ok.has_host() && !not_ok.cannot_be_a_base(),
 
             /* Since we couldn't parse this "URL", then it must be a relative
              * path or a malformed URL. If the URL is malformed, then it will
@@ -328,14 +352,47 @@ impl Scraper {
             Err(_) => true,
         }
     }
+
+    /// Replaces `///` with `//`
+    /// And `//` with `https://`
+    /// Without this function, if url is `///<domain>.<extension>/`, the app crashes.
+    fn normalize_url(url: String) -> String {
+        if url.starts_with("///") {
+            return url.replacen("///", "https://", 1);
+        } else if url.starts_with("//") {
+            return url.replacen("//", "https://", 1);
+        }
+        url
+    }
+
+    /// If the URL leads to another domain
+    fn is_on_another_domain(url: &str, base: &Url) -> bool {
+        let real_url = Scraper::normalize_url(String::from(url));
+
+        match Url::parse(real_url.as_str()) {
+            /* The given candidate is a valid URL, and not a relative path to
+             * the next one. Therefore, we have to check if this URL belongs
+             * to the same domain as our current URL. If the candidate has the
+             * same domain as our base, and the depth condition is satisfied,
+             * then we should visit it,  */
+            Ok(not_ok) => not_ok.domain() != base.domain(),
+
+            /* Since we couldn't parse this "URL", then it must be a relative
+             * path or a malformed URL. If the URL is malformed, then it will
+             * be handled during the join() call in run() */
+            Err(_) => false,
+        }
+    }
 }
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use regex::Regex;
     use std::path::PathBuf;
 
+    use regex::Regex;
+
+    use super::*;
+
     #[test]
     fn test_zero_delay_range() {
         let args = args::Args {
@@ -344,6 +401,7 @@ mod tests {
             jobs: 1,
             tries: 1,
             depth: 5,
+            ext_depth: 0,
             delay: 0,
             user_agent: "suckit".to_string(),
             random_range: 0,
@@ -366,6 +424,7 @@ mod tests {
             jobs: 1,
             tries: 1,
             depth: 5,
+            ext_depth: 0,
             delay: 2,
             user_agent: "suckit".to_string(),
             random_range: 5,