Contact: ThomasKeller

Replaces automate content_diff by a generic automate diff command which outputs the complete changeset (including node adds, drops, renames and attribute changes) in an generic basic_io format. The actual diff is included in a data stanza in unified diff format.

There hasn't yet been an consensus if this should really be the "official" format mtn should use to express external changesets - primarily because once this is set into stone we certainly want an automate apply_diff command to complement this functionality. We also still have to find a way to express binary deltas within this new format to make it really useful for the apply_diff use case.

Status: Stalled for quite a long time, as above