Toraiz Squid Feature Request: Pattern Set Selection by Pattern Change Message from External Device

Currently there is no pattern chain functionality. 

As both a workaround for no pattern chains and as a useful bit of functionality on its own, I propose allowing a Program Change message from an external device to select a new Pattern Set. 

To accomplish this, there should be an option in global setup to activate a Control channel on a specified midi port, where external messages would be received.