Significantly bugfixed persistence and link adding/removal. Not yet fully there, but getting closer to release

Cleaned up and commented major code parts. Refactoring HDD and HSI widgets to support QGraphicsView drag-and-drop, tested multi-MAV support more intensely, currently adding the system coloring to all widgets

Major cleanup of MainWindow constructor. All widgets have now the visible property set to false on its constructor

Added support for MAVLink XML inclusion, added support for multiple Autopilots, improved protocol generation