I was careful in selectively rolling back revisions, but if you've committed changes unrelated to BPY mixed with BPY changes, I might have reverted those too, so please double check.
made all libdata hashable - use the object type,name and lib for the hash.
added .tag to libdata so we can test if data's been processed without using dictionaries
added libdataseq.tag (write only) setting the tag flag (which can always be dirty)
