Program Change reverts to preen presets even if dx7 preset is loaded.

[abelnation]

(This is my current understanding) When I load a dx7 sysex file, I would expect program change messages to select patches from the same dx7 file; however, it appears that PC messages only select patches from whatever the current/last preen bank is currently selected.

Looks like the relevant code is here:

• https://github.com/Ixox/preenfm3/blob/master/firmware/Src/midi/MidiDecoder.cpp#L328
• https://github.com/Ixox/preenfm3/blob/65cb963930c7ce3ceb6bbaa834c9cd00621e207f/firmware/Src/midi/MidiDecoder.cpp#L1368