Cancel ROI support plus many big fixes

More takeoff item fixes

Fix QObject deletion

Fix gimbal pitch/yaw signalling

Fix gimbal yaw visual problems

Fix for vehicle based home position management

New user model for Takeoff item

Fix incorrect usage of _settingsItem causing crashes

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

Fix takeoff item insertion in plan creators

More work getting _addMissionSetting right

Update unit test for no auto takeoff item add

Fix handling of _addMissionSettings

Support for new TakeoffMissionItem and Takeoff Tool 

PolyLine -> Polyline

Polygon/Line tool name changes

Fixed unused variable

Integrate Create Plan overlay in File DropPanel

New centered PlanEditToolbar

Don't set wizard mode on regular waypoints

Fix save state checks. Show overlay on New.

Minimum transect spacing of 0.5 meters

Remove unused variable

Wizard Mode for Create Plan

New Create Plan support

Corridor edit toolbar

Rework presets

More work on mission item indicators