Code review comment for lp:~vila/bzr/conflict-manager

Revno 4668 takes review comments into account:
- settle on using --take-this/--take-other instead of --keep-mine/--take-theirs,
- stop using rest in conflict-types.txt since it's displayed by
  ``bzr help conflict-types`` without processing.

Overall, it doesn't modify any existing behaviour but adds new features
on ``bzr resolve``.

The next steps are described at
 http://wiki.bazaar.canonical.com/VincentLadeuil/ConflictResolution

Discussions may still be needed before the next submissions but this patch
itself shouldn't be controversial.