MIDI support #9

Is your feature request related to a problem? Please describe.

Generating MIDI files from the input would be nice.

Describe the solution you'd like

Implement encoding MIDI files and add an option for selecting between WAV and MIDI.

e.g. linuxwave --output-format midi or linuxwave --midi

Describe alternatives you've considered

None.

Additional context

• https://en.wikipedia.org/wiki/MIDI
• https://github.com/Hejsil/zig-midi