Meter-adapted duration subdivision

First, duration subdivision: notes, rests, dots and ties.

Subdivision of notes and rests is now based on metrical analysis. 
Here are some examples of automatic MIDI import:

- half note at the center of 4/4 bar: 
https://docs.google.com/file/d/0B5alKuFoSol2MjQ0d0JNRVNwZms/edit?usp=sharing

- half pause at the center of 4/4 bar:
https://docs.google.com/file/d/0B5alKuFoSol2U3pkU1UwQUF2cEE/edit?usp=sharing

- pauses and chords near beats:
https://docs.google.com/file/d/0B5alKuFoSol2bWtZRGlYeXUycEE/edit?usp=sharing

- half rest at the start or at the end of 3/4 bar - divided into quarter rests:
https://docs.google.com/file/d/0B5alKuFoSol2OTFTSWpTUTdpTlU/edit?usp=sharing

- example of larger piece of music:
https://docs.google.com/file/d/0B5alKuFoSol2d3Yxbm5jTEYtM00/edit?usp=sharing

- last quarter rest in compound meters like 6/8 - splitted into 2 8th:
https://docs.google.com/file/d/0B5alKuFoSol2eHM5emtXTnR6cGc/edit?usp=sharing

- mixed pauses:
https://docs.google.com/file/d/0B5alKuFoSol2U0ZtM25YaVY1dlk/edit?usp=sharing


Another new feature is a tree-view based frame for selection of MIDI import operations. Now for multiple tracks, if the first row is selected then operations are applied to all tracks simultaneously.

Also there are some changes in MIDI quantization.

MIDI import tests were slightly adapted to new settings. Quantization value is set from program preferences. Test scores were modified: a pair of half and quarter rests was exchanged in each score. That's all - no more changes in tests.

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trig-ger