[rfc] bzr-colo into core

[Alexander Belchenko]

John Arbash Meinel пишет:
> Most interesting for me is to see someone actually using nested
> branching, which is something I pushed for in the model for a long time,
> but haven't seen anyone else really advocate.

Speaking about nested branching: I don't use this layout on the server 
because I'm using trac-bzr, and nested branches are not good for source 
browser in Trac. The simple model is much better fit here.