modify fetch_next_instruction to use instruction buffer.
INCOMPLETE.
rename references to request_read_long_address() to new name that
makes clear that it reads from fastram only.
instructions fetch from fastram to instruction buffer.
make instruction fetches from fastio read into instruction buffer.
instruction execution now runs from instruction buffer.
instruction fetching from IO has a bug.
fixed bugs with instruction buffer.
fix instruction buffer bug
pull in work on 1920x1200x60Hz VGA output.
Can display C64 charset using C64 colours using natural resolution.
work on adjustable character scaling and addressing timing constraints.
continuing to work on character generation.
buffering the read character pixels has solved a major time constraint
blow out.  Need to now make the buffering work by reading the new
pixel row at the right time, regardless of the x scale factor.
work on adding delays to improve timing and fixing remaining issues
with pulling the wrong pixels at the start of cycles.  Still first
pixel is wrong. Also characters are rotated by one bit.
fixed wrong left pixel problem.  still has characters rotated by almost a pixel.
more work on fixing pixel rotation etc. not yet solved.
fix one char pixel rotation problem with character generator.
Now the problem is the one pixel rotation.
fix single pixel rotation problem.  Character drawing seems ok now.
work towards having a border
fix border generation bug. go back to showing all 16 colour characters.
fix bugs with going back to sixteen colour display.
basic border is working now.
change palette to "pal corrected C65 palette".
adjust borders in towards right values for 40x25 @ 4x scale.