ToolStrip rearchitecture for encapsulation and customization

Rework Fly View into separate layers which can be customized at each layer.

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

Visual tweaks for mission items

Plan: Add support for takeoff item required

Put back ToolStrip titles which were mysteriously removed

Drive Plan view ROI support from firmware capability bits

Fix current item updating after delete

Fix Plan insert Takeoff/Land for correct enable state and insert into correct place. 

MissionItemStatus: Show seq nums, clickable selection

Add support for incomplete segment visuals

Remove Fly/Plan from toolstrips

Make Toolstrip flickable, fix maxHeight, fix bunch of margins

Show MapScale at correct times

Active ROI indication in Plan Map items

Cancel ROI support plus many big fixes

More work on contextual Plan tools

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

Only show split indicator on mission layer

Support for new TakeoffMissionItem and Takeoff Tool 

Fix Create Plan vertical spacing problem

Integrate Create Plan overlay in File DropPanel

Fix save state checks. Show overlay on New.

Wizard Mode for Create Plan

New Create Plan support

Fix centerViewport calculation

Fix SplitSegment insertion

Remove all case missing current index notification

Allow split of current segment

Add Terrain toggle to MapScale control

More work on direction arrows

Zoom buttons move to MapScale control

Toggle Rally Point insertion on/off.
Highlight current Rally Point and current Waypoint.
Use tab bar instead of a row of radio buttons for selection (Mission, Fence, Rally).
Fix QGCHoverButton to handle proper checked state toggle.
Get rid of the many arrays used to define behaviors for the ToolStrip. They are now all defined within its model.
Fixed color for disabled text within ToolStrip (it was invisible)