magit-wash-log: cosmetics
magit-stgit--enabled: remove variable and predicate

This was only used to disable the stgit menu entries when stgit is not
"enabled".  It also failed at doing that because it did not properly
invalidate the cache that was used by the predicate.  So we actually
gain something be removing this "feature".
magit-stgit.el: s/--/-/ in symbol names

While using "--" made sense for some of the renamed symbols, it did not
for others which because they aren't (or shouldn't be) internal-only
symbols.  Because we generally don't use "--" in symbol names in
Magit (which some exceptions), replace "--" with "-" in all stgit
symbols.
magit-stgit-extension-menu: move definition
magit-stgit-repair: show message when done
magit-stgit-rebase: show message when done
magit-stgit-mark-patch: renamed from magit-stgit-set-marked-patch
magit-stgit-mark-patch: sanitize refreshing

* Refresh in `magit-stgit-mark-patch' instead of in the call to
  `magit-add-action-clause'.

* Use `magit-refresh' instead of `magit-refresh-all'.  Now wonder that
  was slow (remove todo item mentioning that), the latter refreshes
  everything in every repository (and is therefor in itself a bad idea).
magit-stgit-lines: new function
magit-stgit-read-patch: new function

Also add variable `magit-stgit-patch-history'.
magit-stgit-mark-patch: define as command

and move the definition and add doc-string.
magit-stgit-discard: new command

Previously this was done in the respective `magit-add-action-clauses'
call.  Which would have been okay if that had not acted on the marked
commit (if any) instead of the on at point.  That's not what we had in
mind, when we added "actions".
magit-stgit-show-patch: make use of updated core api

* Adapt to changes in the "mode api" defined in `magit.el'.

* Define it a command, as should always have been done.

* Remove code from `magit-stgit-show-patch' that was copied from
  `magit-show-commit' and was supposed to allow scrolling of the
  buffer, but never actually worked.

* Display stgit patches in a dedicated buffer identified by
  `magit-stgit-patch-buffer-name', as should always have been done.
magit-insert-git-series: abort if magit-stgit-mode is off

The old test didn't make any sense.
magit-stgit-{show-patch,refresh-patch-buffer}: move definitions

The latter is now a bit misplaced, but because it is so short
that is acceptable.
magit-stgit.el: move calls to magit-add-action-clauses

In `magit-stgit.el' move calls to `magit-add-action-clauses' into the
"Mode" section, which now contains all things related to "hooking
stgit/magit-stgit.el into magit", i.e. everything responsible for
modifying hooks and keymaps.
magit-stgit.el: use different types for series and patches

Previously both patch series and individual patches were identified with
the symbol `series'.  Now we use `stgit-series' and `stgit-patch'.
magit-stgit.el: better faces

* Inherit from different faces.
* Change order of definitions.
* Rename `magit-stgit-other' to `magit-stgit-unapplied'.
* Add `magit-stgit-patch'.
* Add `magit-stgit-hidden'.

The new faces are not used yet.
magit-stgit.el: move definitions before refactor
magit-stgit-wash-patch: make use of updated core api

* Make it similar to `magit-wash-log-line' (but don't actually use
  that).
* Use `magit-bind-match-string'.
* Less noise.
* Adjust `magit-insert-stgit-series' accordingly.
* Remove `magit-stgit-wash-series'.