Stuck MIDI keys when testing while already testing

[Asuna Yuuki Nagato]

Steps to recreate:


File->New
Quest->Test; listen for Zelda overworld theme playing
Quest->Test; listen for for MIDI keys stuck on for about 12 seconds while Zelda overworld theme begins playing again

[Asuna Yuuki Nagato]

In play_midi.cpp we have zc_stop_midi()