* Implemetation of MIDI Pass Thru

Successsfully tested on Teensy3.2 and Teensy LC builds

* Soft MIDI Thru now set by byte 8 of config RAM.

* Add Sysex message to force factory reset.

As per #41, it should be possible to remotely reset the EEPROM to
factory defaults. This adds a sysex message that should do that.

* Blank all config slots on factory reset.

Co-authored-by: AtoVproject <atovproject@gmail.com>