Bit of a POC/WIP, maybe not a great idea.
This adds a way to checksum VFS files, which can be used to compare SVN revisions between players somewhat. It's obviously missing the source/ folder, which can be problematic.
Further no GUI support because I'd have to actually add this to the net code and it's not that trivial™.
Hashing works nice and fast though.
Kinda refs #161