Fix logic of when adding Landing item is allowed

Fix unit test crash

Add support for Json file string translations

New LandingComplexItem base class for landing patterns

Major rework to support terrain profile display and terrain collision reporting

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

Small visual tweaks and fixups for patterns

Fix terrain tolerance adjustment step

App messages now use simple modal message dialogs. Vehicle messages continue to use non-modal popup.

VTOL Landing Pattern support

New wizard done model

Drag of land/loiter maintains land distance/heading as appropriate

Out Survey polygons with KML save

Much better mission->kml conversion support

Add support for isTakeoffCommand MissionCommandUIInfo

Fix typo

Remove unnecessary includes of QGroundCotrolQmlGlobal.h

Guard against UI Info not available causing crash

Remove buggy support for generation of incomplete lines

Prevent having items with the same sequence number when the item is incomplete

ArduPilot: Only force MISSION_ITEM_INT if vehicle support bit is set

Always how command description. Better support for VTOL Takeoff. New help text for altitude on Land commands.

Change some descriptions to be more understandable/correct. Change some Heading->Yaw labels. Use new isLandCommand setting.

Survey And Corridor now share same transect generation code. Better unit tests for both with more coverage.

Correct handling of terrain ready when loading back from file

Unit Test for Survey command sequence generation