Must memset structures before use.

Also made combo box widths larger to accommodate text

Remove showSensorCalibrationOrient

Changed (selected) mission item color to primaryButton instead of buttonHighlight
Adjusted some colors for better contrast
Removed a few JavaScript exceptions caused by the order of object destruction

Instead of hardcoded "QGroundContorl" strings

This makes VehicleComponents reusable from core plugin without
requiring override of prerequisiteSetup