This reverts commit  0632851 .
In practice, you can resolve the ambiguities with leading '-' in patch
names.

Also, solve some other `--`-related ambiguities.

The new -G/--git-opts options replace the previous strategy of git options
coming after the -- separator. This allows patch or file names to come
after --. This is more conventional w.r.t. both existing StGit commands and
Git commands.
The -G/--git-opts option may be specified multiple times and supports
multiple space-separated options in each instance. E.g.:
    git format-patch -G--ext-diff -G '--check --binary'
The zsh completions for `stg email` are updated and repaired so that
'--all' no longer expects a file argument and so that `stg send email
--all` is exclusive of specifying patch or file names.
Relates-to: #216

This option provides an alternative means to specify the name of the newly
created patch. The patch name argument requires that a patch name starting
with '-' must be escaped whereas with --name, any valid patch name may be
provided without any escaping.
Scripts and editor extensions should prefer using --name because it
obviates the need to perform checking and possibly escaping user-provided
patch names.
Relates-to: #216

This option provides an alternative way to express patch name and/or patch
ranges to `stg show`.
The --patch option allows any valid patch name or range to be provided as
its value whereas the patch-or-rev option requires patch names starting
with '-' to be escaped.
Scripts and editor extensions should prefer using the --patch option
instead of the patch-or-rev argument because it obviates the need to check
and possibly escape patch names being provided to `stg show`.
Relates-to: #216