Revisions for Targeted Interval N-Gram Output with LilyPond

views/main.py:
- setVisible(True) the targeted n-gram selection QLineEdit

controllers/experimenter.py:
- LilyPondExperiment:
   - doesn't label "horizontal" events that are "None"
   - can add multiple annotations to one Note in annotation part, unless
     they're the same; automatically doesn't label those
- TargetedIntervalNGramExperiment:
   - works