Console text should now be supported on all TGA cards;
8- and 32-bit TGA and 8-bit TGA2 have been tested.
Implement accelerated character drawing, scrolling, and clearing.
Stop clearing "odd" in VHCR; it's unnecessary and hurts performance.
Use bus_space_vaddr() instead of a local hack.
functions based on type returned from tga_getconf().
Adapt to change in ramdac interface.
Fix race condition in tga_sched_update().
Make tga_sched_update() work before interrupts are enabled.
cursor code. These are unneeded on the Bt485, since the RAMDAC handles
the hardware cursor. They are needed for the Bt463, however, since the
RAMDAC only provides cursor color.
