bzr-p4: Perforce foreign branches for Bazaar

[Matt McClure]

I poked around a few months ago looking for Perforce foreign branch
support for Bazaar, and I didn't find much.  I've been hacking on
Robey Pointer's bzr2p4
(http://thread.gmane.org/gmane.comp.version-control.bazaar-ng.general/20710)
a bit.  I've added a few tests to cover the existing functionality,
with a few changes to make it work on Windows for myself.  The test
fixtures use the Perforce Python API
(http://www.perforce.com/perforce/loadsupp.html) and p4d to bootstrap
a Perforce server.  Admittedly, my work so far is immature, and my
understanding of the scope of a full bzr-p4 implementation is naive.
Still, I wanted to share what I have in case others are interested in
taking a look.  My branch is http://mlm.webfactional.com/bzr-p4 .  I
welcome all feedback, positive and negative.

Matt