The gitignore templates used here is from dvcs/gitignore, which is
the same one used by gitignore.io.
Environment variable `FORGIT_GI_USE_LOCAL` is used as a switch to
enable this feature, or the original method is used by default.
`forgit::ignore::update` and `forgit::ignore::get` are rewritten
to download the repo, to get templates from the local repo.
local variable `preview` in `forgit:ignore` is also rewritten to
get the preview from there.
Former-commit-id: c1a8bd71dc
Choose for loop as the solution cause:
- `xargs -d` is not available in BSD xargs
- `echo $@ |tr ' ' '\n'` is slower that for loop in this case
Former-commit-id: 51961b763f
