don't crash on bad timing
32x: start reworking sheduling
32x: rework scheduling/timing

- don't run in line quantity
- decouple from 68k
- some things to tune..
32x: add some comments
save event times to savestates
32x: a hack for dealing with pwm inaccuracy
drc: reload cycles after memhandlers
rm dupe file
sh2: sync sh2 core with latest mame
sh2: timing fixes
drc: lots of new debug code
drc: timing fixes
32x: fix savestates
minor frontend fixes
drc: rework invalidation
drc: rework invalidation yet more

should be reliable now, with overlapping blocks and stuff
drc: some renaming
drc: rework block tracking and lookup

- all 3 caches have their own hash tables (for now?)
- block entry points have separate structures from blocks,
  so invalidation can now properly be done
drc: rework block link tracking
drc: rm write irq check

does more bad than good