bzr diff (and cdiff) should support --exclude option

[Russ Brown]

bzr commit allows me to exclude given paths from the commit. In looking at what I am going to be committing, I would like diff (and cdiff) to support the same option so I can get a consistent picture of what commit will see.

So say I want to commit everything except file foo, currently in order to see a diff of what I will commit, I need to either explcity specify the files I want to commit on the command line when running diff (potentially tedious), or just ignore the file in the diff output (potentially voluminous). The preferable, and more consistent way, would be to be able to pass the same options to both commands:

bzr cdiff -x foo
bzr commit -x foo