opened
jacobtylerwalls
username_0
Fixes #809

The test that had to be adjusted demonstrates the improvement.

```
s = converter.parse('/Users/jwalls/music21/music21/midi/testPrimitive/test09.mid', forceSource=True)
made = s.parts[0].makeMeasures()
made.measure(54).show()
```

**Before**

![voice-chord-before](https://user-images.githubusercontent.com/38668450/106929555-7cf4eb80-66e2-11eb-9345-f69cd540eb25.png)

**After**

![voice-chord-after](https://user-images.githubusercontent.com/38668450/106929570-83836300-66e2-11eb-81ed-ee7558a281a8.png)
Make chord/voice boundary agree with quantization units
issue