Renamed some of the unkXXX variables in the command buffer init

Renamed some of the unkXXX variables in the command buffer init
ialization code.

Note that there are still plenty of actual unknown variables left that should
probably be deciphered.

There are a number of things incomplete in the driver; the different polygon
offset modes (line, point, etc), the other texture filter, texture chroma key,
etc. These should probably be fixed in the future, or at least added to the TODO
list.