Pitch bending

[twilligon]

http://mido.readthedocs.io/en/latest/string_encoding.html?highlight=bend

Test with We No Speak Americano midi

[twilligon]

Perhaps add a new field to Note

I'll have to be very careful on calculating how much of the original note I've exhausted

[twilligon]

This is a better test (and I didn't have to make it)

http://www.buzzwood.com/midi/bend.mid

[twilligon]

I can't crop sounds before rendering efficiently; forgot I was caching the PIL Image object, which doesn't support slicing, obviously. I could try some trickery using Image.crop maybe but that's out of the scope of this issue.