Keyboard interface

[sonph]

Besides the fretboard interface it'd be nice to also have a keyboard interface.

UI: this tonejs example has a rather nice simple keyboard interface

Keybindings: this example already has keyboard bindings e.g. key a -> note C, key s -> note D, key w -> note C#. This will come in handy when the user wants to input notes to do reverse look up.

Sounds: it's nice to have sounds feedback. It's ok to use a synth to generate sounds to keep things light and simple. The tonejs example however doesn't allow for polyphony (multiple notes at the same time). AudioKeys (see test/index.html) has a much smoother sound and allows polyphony. It uses 1-9 to control velocity, but we don't need that. Use 1-9 for quick access list instead.

[sonph]

Related: keyboard library used in Tonejs synth examples Tonejs/tonejs.github.io#8