[SoC] Rebase feature - Update

[Stefano Tortarolo]

Hi,
	a lot of work has been done so far, I've made the corrections suggested 
by Patrick (except the wlock one, I'll start another thread about this 
later), so it's now possible to rebase to a non-head revision, etc... 
and I've started working on more advanced features.

The current code allows users to resume a rebasing process after a 
conflicting merge or interruption. This is a very tricky point, so 
please test the code and report any problems/bugs.

When dealing with conflicting merges, the user solves the conflict, 
removes any .orig files and runs hg rebase --continue. 
(test-rebase-conflict for more information)
Does this look reasonable to you?

As usual, the code is here: http://freehg.org/u/astratto/soc/

Cheers,

Stefano