Generalise dired fontification

There is no need to limit it to the denote-directory.  We ultimately
want to fontify all Denote-style file names, not just the notes created
by Denote.

For example, I have been recording all my longer-term storage using such
a naming scheme: this mode gives me the extra faces for .pdf, .mp3, and
other files.

Users of Denote may want this for attachments.

The upside of having this as a buffer-local mode is that the user can
write a wrapper function that applies the mode only in a given
directory (like we were doing before).

Thanks to Ypot for suggesting a kernel of this idea in issue 1 over at
the GitHub mirror: <https://github.com/protesilaos/denote/issues/1>.

README.org

@@ -370,7 +370,7 @@ Denote is meant to be a collective effort.  Every bit of help matters.
 
 + Author/maintainer :: Protesilaos Stavrou.
 
-+ Ideas and/or user feedback :: Kaushal Modi.
++ Ideas and/or user feedback :: Kaushal Modi, Ypot.
 
 * GNU Free Documentation License
 :PROPERTIES:

denote-dired.el

@@ -88,18 +88,14 @@
 (defun denote-dired--setup (&optional reverse)
   "Setup `denote-dired--fontify' local hook.
 If optional REVERSE is non-nil, remove the hook."
-  (cond
-   (reverse
-    (setq dired-font-lock-keywords denote-dired-original-keywords))
-   ((or (string-match-p (denote--directory) default-directory)
-        (string-match-p (abbreviate-file-name denote-directory) default-directory)
-        (string-match-p denote-directory default-directory))
-    (denote-dired--fontify)))
+  (if reverse
+      (setq dired-font-lock-keywords denote-dired-original-keywords)
+    (denote-dired--fontify))
   (font-lock-refresh-defaults))
 
 ;;;###autoload
 (define-minor-mode denote-dired-mode
-  "Integrate denote with Dired."
+  "Fontify all Denote-style file names in Dired."
   :global nil
   :group 'denote-dired
   (if denote-dired-mode

denote.el

@@ -112,7 +112,7 @@ specifiers."
   "Regular expression to match `denote-keywords'.")
 
 (defconst denote--file-regexp
-  (concat denote--id-regexp denote--keyword-regexp "\\(.*\\)\\.org")
+  (concat denote--id-regexp denote--keyword-regexp "\\(.*\\)\\..*")
   "Regular expression to match file names from `denote-new-note'.")
 
 (defconst denote--punctuation-regexp "[][{}!@#$%^&*()_=+'\"?,.\|;:~`‘’“”]*"