recent changes

[Martin Pool]

Hi, just an update on what I've been up to:

Revisions now allow for tracking multiple parent revisions; those
after the first are the revisions that have been merged-in.  This is a
slight adjustment from what was previously planned, where the first
revision would be stored specially.

Cherrypicked changes or removed changes need to be recorded
separately.

I've also started cleaning up testbzr so that both the whitebox and
blackbox (run "python bzr") tests are handled in a single framework
based on unittest.

-- 
Martin