Port "Categorized random questions" questions into D7

I needed this on a site I am building and I gave porting this feature into D7 a try. I think I got it to a fairly stable point, however, I believe there are still issues that are outside of just porting this, like the auto-versioning which doesn't seem to be working properly. I have only done a few tests, not enough to do a proper review, and unfortunately I decided to swtich to D6 for the time being, but I wanted to leave the patch here for future reviews or as a starting point.

Please note that most of the D7 conversion are in place and that the feature is "functional".