Handy for testing without a real board

* The "Simulation" option is now not selectable.
* If the link is a simulation, then you can't change it to a different link type.
* The OPAL option is not shown if support is not compiled in.
* Fix the buddy, tab order and accelerators in the GUI.

Set the remote address of the xbee via the xbeeconfiguration window and save last address in a txt file. Xbeelink ist still hardcoded to work with series2 xbees

Cleaned up serial link handling, eliminated double menu entries and safeguarded the link list. Did intentionally not improve the object dependency issue, will work on that on a global scope

Added not yet working version of logging / log replay, fixed ALL bugs in main window, enabled full persistence in main window and serial link.

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.

Cleaned up communication structure significantly, should now be easier to add new links. Signal bytesReceived(link, QByteArray) is now only way to pass on newly received data

(cherry picked from commit c3194971)