[MERGE] Implement guess-renames

[Talden]

> This patch implements a guess-renames command.  Assume some other
> process has renamed some of your files.  This will guess what renames
> were performed and update bzr accordingly.

Could this (or does it already) support a --dry-run option (or
similar)?  If there are many many files, have it apply the changes
immediately might not be preferable to reviewing what it's going to do
first.

Could this be an option of mv

    $ bzr mv --guess --dry-run

This is a great new feature, and non-bzr futzing with the tree being
as common as it is, making it a built-in feature is a good idea too -
users shouldn't have to go hunting for a plugin for this (or make it a
standard plugin).

--
Talden