Ardupilot support, builds now cleanly on Windows. Fixed a bug where the application could crash if no system was connected.

Fixed bug in check for osg/osgEarth dependencies for QGC. The Q3DWidget instance runs if OpenSceneGraph libraries are installed. The terrain feature is enabled if osgEarth libraries are installed.

Still need to add uas connections. New osgwidget inherits from
qgraphicsview to expose more functionality to qt. Map3d.ui contains
the graphics view and some buttons. Currently runs yahoo_heightfield
by default. Make sure you run qgroundcontrol fromt the top dir or
it will seg fault, :-). I'll add some error handling soon.