[Version Control System] Subversion 1.7

Full support for Subversion 1.7.

The following are subject to be added:
- [x] Fully runnable UnitTests for Linux, not just one by one runnables. This is due to svnserve being a nasty daemon which doesn't care about Process.Kill ().
- [x] 1.6 Windows AddIn for backward compatibility.

The following are subject to change:
[ ] Commits can be squashed in the near future.