Make it possible to detect a BoundBranchOutOfDate from commit.
* ``bzrlib.builtins.Commit.run`` raises ``bzrlib.errors.BoundBranchOutOfDate`` rather than ``bzrlib.errors.BzrCommandError`` when the bound branch is out of date. (Gary van der Merwe) * ``bzrlib.errors.BoundBranchOutOfDate`` has a new field ``extra_help`` which can be set to add extra help to the error. (Gary van der Merwe)