Merged in new ripping code

I haven't been able to test this on a working DVD. There are a couple of TODOs:

* driveLetter isn't used: makemkv uses disc numbers (0: first drive with disc, 1: second...)
* makemkv can't read some DVDs (it didn't work with my copy of Gattaca)

We'll have to change this soon, but I think it's a good starting point.