MIDI input and Gate Input expander

This expander adds more features to Bard Quartet. It provides individual gate inputs, allowing independent Track & Hold and Arpeggio reset per channel. It also allows processing MIDI notes in three ways:

• MIDI-controlled quantization (quantization is based on incoming MIDI notes)
• quantized MIDI (module quantizes incoming MIDI notes according to current scale settings)
• MIDI-to-CV conversion