Factor out key=>sym/string code and remove use of deprecated XKeycodeToKeysym.
Factor out key=>sym/string code and remove use of deprecated XKeycodeToKeysym.


OpenMusicKontrollers/moony.lv2,drobilla/pugl,OpenMusicKontrollers/patchmatrix,OpenMusicKontrollers/moony.lv2,OpenMusicKontrollers/synthpod,harryhaaren/pugl,OpenMusicKontrollers/sherlock.lv2,harryhaaren/pugl,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/synthpod,harryhaaren/pugl,drobilla/pugl,OpenMusicKontrollers/sherlock.lv2,OpenMusicKontrollers/moony.lv2,OpenMusicKontrollers/patchmatrix,OpenMusicKontrollers/patchmatrix,OpenMusicKontrollers/midi_matrix.lv2,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/midi_matrix.lv2,OpenMusicKontrollers/midi_matrix.lv2,OpenMusicKontrollers/moony.lv2,OpenMusicKontrollers/moony.lv2,OpenMusicKontrollers/moony.lv2,drobilla/pugl,OpenMusicKontrollers/patchmatrix,OpenMusicKontrollers/sherlock.lv2,OpenMusicKontrollers/sherlock.lv2,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/midi_matrix.lv2