The diff parser code was rewritten for clarity and speed and now handles
a couple of ugly cornercases, like SVN's property change output and single
change chunks, much better. Since the path parsing was unified as well,
the SCM interface gained a new method `getPathStripLevel()` which determines
how many path components need to be shoven off a file name for the SCM
to form a valid path in the workspace (similar to patch(1)'s --strip option).
Fixes issue 627. Automated tests follow.
We now have a limited support of the code review. Still some work to be
done to allow the submission of new patches on a given review and update
the status. For the moment, only pre-commit review is supported.
