[MERGE][RFC] Add simple revision serializer based on RIO.

[Ian Clatworthy]

Ian Clatworthy has voted comment.
Status is now: Semi-approved
Comment:
A performance improvement would be one of the main reasons for including 
this or otherwise. I'd like to see this patch resubmitted so that this 
serialiser is used in a proposed new development format. (At first 
glance, it looks like your changing the behaviour of an existing 
format?) I can then more easily benchmark its impact, report the results 
and vote accordingly.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C49FC3ED0.7060601%40samba.org%3E
Project: Bazaar