Large commit. Test roms now partially run.  Extremely slow.
Input, some speedups
Speedup to 0m20.531s.
Performance improvements.
major speedup; pc is a regular variable
Fixes, now runs PKMN Red intro.
Minor fixes.
Refactor registers.  test.gb parity, slightly faster.
More corrections.  Pokémon Red runs properly with only slight graphical issues.