MPGuino- quick weekend build

This weekend we found ourselves wishing to take some time off the main project which is progressing smoothly enough. So we grabbed a spare beat-up Arduino and built up an MPGuino. We're sneaky and connoisseurs of the analog era, so we're swapping out the plebian Zener diodes for some more bourgeois optocouplers on the injector and speed signal lines.

Should be a fun build!