More work on Plan sync user model

Palette adjustments

Plan-ToolStrip: Fix button visibility

Changed (selected) mission item color to primaryButton instead of buttonHighlight
Adjusted some colors for better contrast
Removed a few JavaScript exceptions caused by the order of object destruction

New Plan a mission sync/save user model

General Settings tweaks.

New file save settings and desktop/mobile file dialog capability

New Takeoff, Start Mission, Resume Mission

Better initial map positions and planned home position support

Plan: Fix bad sequence numbering

Exponential Slider

Add flightDistance to Vehicle FactGroup

Plan toolbar: Qml warning fixes

Hide plan toolbar when switching views

New Follow Vehicle user model

Fly: Click to set new mission item

Plan: Support for Mission End Actions