Additional pedal functions

[hugbug]

In addition to standard pedal functions (#69) there are other useful things the pedals can do (which Smart Pianist doesn't support):

• play/pause song;
• activate/deactivate stream lights;
• change stream lights speed (fast, slow);
• activate/deactivate guide mode;
• start/stop metronome (once we have metronome);
• select fragment for playback loop;
• activate/deactivate left voice or layer voice;
• local control on/off (loudspeaker button on the toolbar).

In this issue we'll investigate if it's possible to perform custom pedal actions in ConPianist. It's important to ensure that piano doesn't perform any actions on their own if we intend to process pedals in ConPianist.