Doxygen improvements: more modules, added faked containers so that they are properly recognized
Plugins: Major rework of the DMX USB plugin to support all the Pro widgets features.

This fixes the simultaneous input/output on the same device.
Now the Pro Mk2 supports also MIDI input/output.
Code cleanup. Removed a bunch of overloaded classes.
Added Pro modes grid to DMX USB plugin documentation.
Fixed documentation style CSS
Fixed DMX USB plugin Windows build
Plugins: propagate a return value on openInput and openOutput

This is to be able to display an error message to the user if something went wrong with the physical device
Updated translations (UI and DMXUSB changed)