Directions arrows in Fly View

Fix initial load for Plan view

Fix missing waypointLinesChanged signal. Remove unnecessary directionArrowChanged signal.

More work on direction arrows

New MapLineArrow control

Make visibility work

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)

There are no editable parameters and without this, you are presented with a raw list of all 7 parameters to edit.

Update all files that use a QML Menu item to QtQuick.Controls 2.4 to solve the issue of a menu showing up in random places on Android.

Fix incorrect reference to vehicle causing crash

Tree contains all commands

Add support for geofence return point. Also fixed a bunch of bugs in geofence and rally point support.

Fix incorrect isManualCamera logic

Fix initialization

Pattern Preset support

Change-Id: I80acc497ef8fc574f64b181a8d276c5b00d4e057

Heading: Switch from Radians to Degrees

Work around quirkiness with ArduPilot and LOITER_* NaN handling on heading.

No camera commands for ArduPilot

Get rid of QGCView, QGCViewPanel and FactPanel. All messages and dialogs are now handled in the root window.

BUGFIX: When scanning from the top the starting altitude shall be equal to the structure altitude.

Hack around ArduPilot problems with unsupported NaN in Loiter commands

Structure Scan turns on Survey photo mode

Fix layer heights

More work on Structure Scan rewrite

Bug fixes for Structure Scan. Also includes support for Entrance/Exit Alt.

Add support for Start From Top/Bottom, plus more helpful stats