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
Engine: (huge one) unified InputMap and OutputMap. Universes saved on project XML (not loaded yet)
Engine: InputOutputMap and Universes are now loaded from XML
Add doxygen configuration file and comments

For more info on doxygen, see doxygen.org.
For install in Ubuntu/Debian, run "sudo apt-get install doxygen graphwiz"
Generate source documentation/browser with "doxygen qlcplus.dox" in doxygen/
Remove unused class DMXSlider

Should have been removed in e639f2d
Rename OutputPluginStub to IOPluginStub, as it better expresses the purpose
Refactoring: add InputPatch::isPatched(), OutputPatch::isPatched()