Simple VGA Graphics.

Well, it's a few months later than I planned, but I have basic VGA support
(320x200x256) built into movitz now.

Example screenshot here:
http://www.bealbywm.plus.com/movitz/ss.png

Once I actually understood what was required to get into graphics mode, coding
it was actually very easy.  Converting the image to the correct format took
much longer.

I'm going to flesh out some more graphics functions over the next few days and
get a diff made up so everyone can have a play.

Thanks everyone,
Martin