Experimental UNDO

Undo should work in edit mode in my verse-blender. Ton proposed to resend whole mesh geometry after each undo step, but my solution is more tricky and effective. It sends only different between undo mesh and verse mesh. I fixed one stupid bug and I did cvs merge yesterday. Keep testing! Ehm, undo doesn't work in object mode yet. You can find Linux binaries and source code at usual place.