add comments on what to do when I have free time again.
add comments to remind myself what next needs to be done with the
program, including the option to eliminate the overscan border because
the PEXHDCAP is mistaking the overscan border as part of active picture.
BAT files updated
ok
correction: vga240.c needs to consider vtotal constant is total - 2, and
vdisplay end constant starts out as display end, but is subtracted by 1
before writing, and when reading display end from CRTC, needs to add 1.
add option to toy with overscan color for testing