Represents a musical score
MusicScore[{voice1, voice2, …}]
MusicScore[{event1, event2, …}]
MusicScore[{{event11, event12, …}, {event21, event22, …}}]
MusicScore[events, ts, ks]
MusicScore[events, ts, ks, properties]
MusicScore[music, events, ts, ks, properties]