More takeoff item fixes

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

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

More work getting _addMissionSetting right

Fix handling of _addMissionSettings

Support for new TakeoffMissionItem and Takeoff Tool 

Fix save state checks. Show overlay on New.

Remove unused variable

Wizard Mode for Create Plan

New Create Plan support

More work on mission item indicators

Fix SplitSegment insertion

Allow split of current segment

Remove unnecessary signaling

Use QmlObjectListModel::begin/endReset to keep Qt from blowing it's brains out with too many updates

Remove testing ifdef

Directions arrows in Fly View

Fix initial load for Plan view

More work on direction arrows

Structure Scan turns on Survey photo mode

Use correct QT_TRANSLATE_NOOP to prevent crash

Support for new AltitudeFactTextField

Expose complex item names in a way useful for custom builds

Support custom build override of available complex items

Fix handling of dirty bit when home position changes from vehicle side

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Fix planned home position set when takeoff has no coordinate in it

Fix terrain NaN making it all the way to Planned Home altitude.