More takeoff item fixes

Fix QObject deletion

Fix gimbal pitch/yaw signalling

Fix gimbal yaw visual problems

Fix show/hide of click to set Launch location

Better wordings for Takeoff item

Fix for vehicle based home position management

Remove unused code

New user model for Takeoff item

Fix gradient calc

Fix incorrect usage of _settingsItem causing crashes

Group parameters with no metadata with the other existing params in the group, not in "Other"

Error display

Fix reference to settings from wrong thread

ADSB server support provided through new ADSBVehicleManager implemenation

More work on contextual Plan tools

Fix center drag and split side

A contextual Land/RTL tool. Better waypoint line calc.

RTL is no longer part of Mission Settings