There was one bug that went undetected in the v65C02 core (in STX ZP,Y)
and another in the 80STORE handling (80STORE doesn't affect reading).
Also added a pause mode (bound to the Pause key), for those times when
you need to walk away from the emulation for a bit.
Before it was doing some complex timestamp thing, now it simple runs the
CPU for ~21 cycles and then stuff the sample into the sound buffer.
Sound still lags behind by several frames though, just like with the
previous sound setup. Still not sure why. :-/
