[in progress] merger of tree-reference and dirstate

[Martin Pool]

At Robert's and Aaron's suggestion I have been merging the
tree-reference and dirstate branches, so that 0.15 will have a format
that supports both subtrees and faster working directory operations.

The branch is at http://sourcefrog.net/bzr/dirstate-plus-subtree

It is now passing all the tree-implementation tests for dirstate holding
references.  A few dirstate glitches have been fixed on the way.  My
next plan is to remove the tree-reference workingtree format Aaron added
in favour of only having dirstate provide this feature, and see if that
finds any other problems.  Also I want to review the overall delta
between dirstate and this and see if there's any unnecessary cruft.


-- 
Martin