- Initialize more of the Bt463's registers, instead of leaving them
in undefined states. Notably, the window type table is set up
with 8-plane pseudocolor and 24-plane truecolor modes.
- Bus-space-ify, mostly. Could use some more cleanup, but not until
the rest of the tga stuff is converted, too.
- Do the TGA/RAMDAC communication dance more carefully.
- Explain a lot more of what's going on in comments.
nathanw