Onset Snapping
Chiu 1999, Mazurka 7/2:
   iteration 1 mean deviation: 10.5 ms
   bello snapping md:             13.4 ms
Friedman 1930, Mazurka 7/2:
   iteration 1 mean deviation: 22.0 ms
   bello snapping md:             22.1 ms
• Snap earis to bello if a bello onset is less than 50 ms away.