[merge] split out repository formats

[John Arbash Meinel]

John Arbash Meinel has voted +0.
Status is now: Semi-approved
Comment:
I think we decided to bring back a couple things like InterWeaveRepo. 
And we need to figure out how we want to handle compatibility.

But I really like splitting things up.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C20070206063924.GA1855%40sourcefrog.net%3E