working on mmc5 scanline counter, laser invasion is working now, something is fishy with Just Breed
changed mmc3 counter behavior a bit so it keeps resetting timer on getting new rising edges very quickly in a row.
dummy reads for mmc5 should only happen when ppu is on
fixed mmc5 ExGrafix mode
finally got the mmc3 scanline counter to both pass blargg's tests and run mega man 3, but I did have to add yet another method to the mapper class to do it. (Just reading if the PPU is off broke the MMC5 counter instead.) Now to fix every other mmc3-based mapper.