[MERGE] Implement generic stacking rather than pack-internals based stacking.

[Robert Collins]

This is now ready for final review. This patch contains:
 - a Development1 format which is stackable on any repository with
matching serialiser and model
 - various tests and refactoring to support that..

Attached is a full bundle, and a plain text diff of the incremental
changes (which show the removal of the changes made to be able to use
the internals of packs, back to doing purely interface based stacking).

AFAIK this is all reviewed and good to go except for the incremental
change that I've attached.

-Rob


-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Development1-3240.patch
Type: text/x-patch
Size: 64543 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20080625/0de290f3/attachment-0002.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: internals-to-generic.patch
Type: text/x-patch
Size: 16208 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20080625/0de290f3/attachment-0003.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20080625/0de290f3/attachment-0001.pgp