user/jszakmeister: create some specialized mappings for ``git rebase``
user/jszakmeister: highlight diffs in emails
user/jszakmeister: treat certain patch files as email

This is useful when editing patch files generated by `git format-patch`
or `git send-email --annotate` when sending patches to a list.  You
often include information below the --- marker in response to feedback
on the list.
user/jszakmeister: teach gV to match the original visual selection mode