Sensor Cal: Handle case where no mag present [continued]

Cleanup layout issues throughout QGC

Mavlink Console Improvements

CameraCalc: Image Density -> Ground Res

Adjust to new parameters in Copter 3.6

Simplify PreFlightCheckButton implementation

Includes support for battery 2 setup

PreFlight: Style cleanup and changes

* Added support for sat count to Sensors check control

Create standalone controls for PreFlight CheckList

PreFlight Check List: Control renaming

More commonly known terminlogy

* QGCCheckListItem -> PreFlightCheckButton
* CheckList -> PreFlightCheckList

Pre-Flight Checklist: Coding style cleanup

Survey: Support for flying alternate transects (fixed wing only)

Plan: Large progress bar in Outdoor theme

Better help for alt mode

Generic PID tuning support

Allow custom build to hide Absolute Altitude in mission planning

CameraCalc: Add missing update triggers

Fix standalone coords affecting time/distance

Fixed Wing Landing Pattern: Visualize landing area