Major update to simplify and document the custom build example

Major update to simplify and document the custom build example

Make QGCMapPolygon area accessible in QML

New LandingComplexItem base class for landing patterns

New LandingComplexItem base class for landing patterns

Major rework to support terrain profile display and terrain collision reporting

Fix more QTime deprecated functions

Fix OSX compile

Update

Major rework to support terrain profile display and terrain collision reporting

Show mission items in Geofence edit mode

Propagate opacity and interactive properties to mission items
Set opacity to 0.5 for items that are not part of the current
edit view

Excluded ANDROID OS from LINUX variable in cmake

Fix MissionManager (cmake)

Small video tweaks