implement timer+Vblank interrupt

[djmaximum17]

the current version of Game Music Emu doesn't play GBSs that make use of the timer+Vblank, they just stay silent. attached is a zip that has some GBSs that have the timer+Vblank ability

[Wohlstand]

Continue at new repo: https://github.com/libgme/game-music-emu/issues/48