Drums in MIDI import

Here is a MIDI import of drums:
https://docs.google.com/file/d/0B5alKuFoSol2clRvMk5TYWtkZVU/edit?usp=sharing

Also there is an option of a drum staff splitting:
https://docs.google.com/file/d/0B5alKuFoSol2YTJUcEF5LXNjR1E/edit?usp=sharing


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Before this pull request drums were imported as piano notes and sound:
https://docs.google.com/file/d/0B5alKuFoSol2RFNWbmU1akNxQ1E/edit?usp=sharing