[PATCH] delta creation

[PATCH] delta creation

This adds the ability to actually create delta objects using a new tool:
git-mkdelta.  It uses an ordered list of potential objects to deltafy
against earlier objects in the list.  A cap on the depth of delta
references can be provided as well, otherwise the default is to not have
any limit.  A limit of 0 will also undeltafy any given object.

Also provided is the beginning of a script to deltafy an entire
repository.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>