Add MIDI file playback

[jameshball]

Should be fairly easy using something like this: https://stackoverflow.com/questions/26266411/java-midi-how-to-get-notes-from-midi-whilst-its-playing

This would lend itself to creating another section in the interface for controlling MIDI - maybe under the audio effects panel? This should probably be collapsible to save on space in the interface.

[jameshball]

Closing as this osci-render 2.0 is an audio plugin so it's really easy to play a MIDI file from within a DAW