Console Based iPad Tuning

On the heels of the console handling pipe processing, we are now able to handle chamber iPad MIDI at the console and send it to the chamber on the PipeBus link.

MIDI channels simply get pointed to an empty keyboard buffer, which is processed by the console like all other keyboards, and tuning stops get pointed to unused console stops, which are also treated like regular stops.  Additional P.stp_seg statements allow the tuning notes to merge with the console notes.