Add support for encodeing and decoding raw binary MIDI messages

[oubiwann]

There's a lot to cover in the MIDI specs, so we'll keep it simple at first.

Note that the impetus for this feature is the experimental epic issue+branch in the midiserver project where the Erlang NIF from Sonic Pi is being used to send bytes directly to MIDI devices

Tasks:

• [x] Create new module, midibin
• [x] Create midibin:encode function
  • [x] support aftertouch/1
  • [x] support note_off/1
  • [x] support note_on/2
  • [x] support pitchbend/1
  • [x] support cc/2
  • [x] support program_change/1
  • [x] support reset/2
  • [x] support sys_ex/1
  • [ ] support channel/1
  • [ ] support the non-standard (midilib-only):
  • [x] batch/1 and batch/2
  • [ ] support bank_select_msb/1
  • [ ] support bank_select_lsb/1
• [x] Create midibin:decode function
  • [x] support aftertouch/1
  • [x] support note_off/1
  • [x] support note_on/2
  • [x] support pitchbend/1
  • [x] support cc/2
  • [x] support program_change/1
  • [x] support reset/2
  • [x] support sys_ex/1
  • [ ] support channel/1
  • [ ] support the non-standard (midilib-only):
  • [x] batch/1 and batch/2
  • [ ] support bank_select_msb/1
  • [ ] support bank_select_lsb/1

[oubiwann]

Calling it done.