MIDI mapper: do not override user choices.

This patch removes an optimization feature that disable acceptControlChanges and acceptNoteChanges at low level. This was used to prevent CPU overload to process unused CC or notes, have more side effects than benefits: that prevents ConfigDialog to connect to newly detected MIDI devices.
LedMatrix: move hardcoded size value from LedMatrix to Minotor class
Minotor: settings (MIDI interface, serial interface, etc) are now handle by Minotor class
Minotor: load settings after instanciation
Settings: store renderer size