Implementation of Battery Monitor configuration, and addition of AP2ConfigWidget, which automatically handles UAS connections to allow for simpler configuration window code.

Removed OpenGL dependency in HUD, merged in HUD from Soren Kuula and config changes from Michael Carpenter

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

Change so Waypoints are the same across maps, and offline waypoints get appeneded to the end of the MAV's waypoint list on connect

Addition of new "User" param for apm.pdef.xml file, allowing for sorting config entries between general and advanced tabs

Variable calibration procedure text based on the autopilot, stored in files/%autopilot%/general/calibration/description.txt.
Added a new QGCTextLabel type for QGW files, which can display MAV text or hardcoded text.
Added tabular configuration screens based on folder structure inside the files/autopilot/airframe folders

This commit still allows configuration widgets to be loaded from qgc files
assuming that there is no APM generated xml file (arduplane.pdef.xml) in
the files/%autopilorname%/ directory. This filename needs to be
configurable, and selectable at runtime. It is not yet.

APM configuration, battery and extra sensors

added Rascal airplane model for flightgear which also includes a 3D model (from http://flightgear.org/legacy-Downloads/aircraft-2.0.0/)