MIDI Polyphonic playback routine

[oggy22]

Write a method which plays back a musical piece (e.g. read from midi file) to audio. It should:

• be able to play more than one track polyphonically
• be made flexible with 2 callback: PlayNote and StopNote, so it doesn't necessarily need to use midi output, but also some other audio outputs when available
• be used at least at two places 1) main program with midi input 2) in WPF when on "play" button pressed
• be a method on the class MusicalPiece, which needs to be introduced prior to this.

[oggy22]

Or it can still use midi output but enrich with overtones for example (pertaining to 2)