Play or not part of the music depending on the flags

[sikthehedgehog]

Currently the flags are mainly used to let the 68000 know where the music is currently, but they could be put to better use. Making some events trigger conditionally depending on the flags would allow for music to adapt on the fly depending what's going on in the game.

Maybe could tie in with #22, making it conditionally play/jump to chunks.

[marcb0t]

Haha! Right on!

Add some Ocarina of Time style music transitions into some Genesis games! :)