Partway through refactoring of UAS deletion. This is in order to actually support removing UASes from QGC, which is currently impossible.

Impl. Lorenz suggestions wrt one velocityChanged, altitudeChanged, speedChanged signal per reference frame. Impl. CDI on compass disk.

Changes for new calibration in APM 3.0 (Re: https://github.com/diydrones/MissionPlanner/issues/38), and change in some of the serial timeouts

Fix for crash when removing item from QuickView, and addition of more generic signal/slot combonation for property updates

Removed a lot of verbose debug output, added connection indication to main menu bar to improve situational awareness of operator

Added a unit test, setAirframeTest. Changed setAirframe function. Added an end_of_enum to the airframe enum.

Added remote OpenGL drawing in 3D view. Any external application can draw to the 3D view via the protobuf implementation of GLOverlay messages.

Removed some dead code.
Added more valueChanged() signals to account for every data type. This moves the conversion over into the valueChanged receivers, which while it will require more slot-functions, makes it easier to add more code as any necessary conversion is done internally to the slot and so the signaler doesn't need to know the details.
I also added some more details on the types of units expected by valueChanged().

Exposed HEARTBEAT.system_status and HEARTBEAT.base_mode to the realtime plotter widget via the valueChanged signal.

Added multi-UAS support to QGCRGBDView. Fixed display timeout issue on computer for which data source is not time-synchronized.

Added visualization of obstacles. Fixed relative font path issue in 3D widgets by using QFont within osgText::Font instead of using static font filename.

Enabled visualization of point cloud data via Protocol Buffers serialization and extended_mavlink_message.