Turn off new compiler warning

Switch from android-g++ to android-clang

Move android build to ndk r20 and Qt 5.12.4

Updates for Qt 5.12 and 64 bit

Feature Proposal - Home Heading / COG Angle / Next WP Heading in Compass

SerialInterface: delete - it's not used thru the project

Plan View Work

Add Sony DSC-RX0 Camera

MissionItem memset to 8 instead of 0

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)

Remove all references to Pairing if it's not supported.

CameraManager, improve displayed available memory

custom-example: Add GPS info to the Vehicle Indicator

Fix `VERSION` qmake variable being corrupted by dev version build

Initial support for link pairing

Pr fix combobox usage

Enable video running time and shutter count

Global: change null or 0 to nullptr

Fix for android builds (attempting!)

Fix for android builds

64 bit serial fixes

qobject_cast is times faster dynamic_cast for objects that
inherit QObject. also, use auto keyword to not duplicate
class names.