Fix setting of foldmethod in :Gstatus

Closes #300.
Switch :Gblame <CR> to open commit

This is more useful than the previous behavior of reblaming at that
commit.  Said behavior is still available on -.
Fix :Git! on Windows.

Closes #301, #302.
Unify escaping rules for :Gedit with :edit

In particular, this makes `:Gedit file\ with\ spaces` work, and updates
the tab complete to match.

Closes #305.
Work around archaic encodings

Closes #304.
Add foldlevel to fugitive_diff_restore
Expose detect interface

Closes #311.
Seek to blob name in tree with -
Include tree filename in <C-R><C-G>
Change cp to cP

This has the incredibly self-serving purpose of paving the way for
evaluating Clojure in historical buffers.
Add . to prepopulate command line with revision
Don't dispatch autocommands when calling git commit

Closes #295.
Loosen regex to compensate for iskeyword

Closes #332.
Add foldenable to fugitive_diff_restore
Revert "Add foldenable to fugitive_diff_restore"

This reverts commit cbb7c3e89026472dfbc5440d78ce85975423bedd.
Encapsulate restore options for diff

This should make it easier to experiment with solutions for issues such
as #257.
Press - on first line of :Gstatus to edit .git

This is a bit silly, but provides a quick way to start navigating the
repository.  Press it a second time and you're in the work tree root.
Change heading style
Extract contribution guidelines
Update :Gblame explanation in README