[MERGE][#175520] use historical context for file logging

[Adrian Wilkins]

> If we start supporting file-ids in the UI, I'd like to do so
> across every command and allow you to specify "fileid:..."
> anywhere you can currently specify a file.


+1 on supporting file-id ; when the FAQ of "how do I find the revision a
file got deleted in" came up for the Nth time in IRC, my first impulse
was to implement a --file-id option for `bzr log` which is relatively
easy since it just resolves them internally anyway.

Of course, because of the way inventories are stored, it doesn't make
this operation any cheaper or much easier. Does split inventories fix
this - is it cheaper to determine where a file was deleted because the
deletion is marked by a "deleted" delta instead of "poof! it's not in
this revision anymore"?