This is done via MI_BENDD and MI_BENDU. At the moment the value is
hardcoded and cannot be adjusted (future commit?) and is the max for the
`midi_send_pitchbend` function (up or down).
`MI_BENDD` and `MI_BENDU` both require `#define MIDI_ADVANCED`
MIDI pitch bend was already implemented in `protocol/midi.c`, I merely
added the keycodes to trigger them. :) (thanks to Jack, two years ago
in commit fb4fe52c apparently)
3d3c093173