Engine: This is huge. Split universes. Also:

- Grand master now has its own class
- Relative write has a dedicated call

Not working:
- HTP/LTP
Engine: fixed crash on Universe write

- added channel capabilities API and called when a fixture is added
Engine: fixed crash on SimpleDesk and Monitor
InputOutput manager: given a stylish look
Input Output manager: it is now possible to add/remove universes
Engine: finally solved weird behaviour caused by wrong channel capabilities mask !
Simple Desk: reviewed/simplified code with the new multiple universe code. Simple Desk is now always the last DMXSource so it has precedence over all DMX values