MQ support:
- Added `Hgqseries` command to navigate MQ series.
- Ability to go to, rename, and edit the message of a patch.
- Wrote documentation.

Fixed a bug with the `Hgstatus` being `readonly`.
Made the `Hgstatus` window refresh itself when needed.
Changes and fixes to the `Hglog` window:
- Fixed a bug with showing diffs.
- Made the diff behaviour and commands more consistent with those of
  the `Hgstatus` window.