Add gimbal to external control signal

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.

Move PreflightCheckList to custom builds only. The model, which used to be implemented within BuiltinPreFlightCheckModel is now within the control itself. It is up to the implementer to define a proper model.

Fix height

Fix typo

New qml base log replay status bar

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Restored FirmwareUpgrade.qml as it was beyond repair. Also fixed some issues that were present in the original, master version.
Added "hasAPMSupport" to QGroundControl global control. This is to determine if APM support is enabled or not.

When the item is not visible, the width and height are not valid,
resulting in wrong output values
Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Fixed places where the font family was not being defined (therefore using the default system font)

Use regular sliders

PID Tuning rate adjustment

Turn on live updating for vehicle facts used in PID charts

Make ToolStrip font smaller (Desktop builds)
Check for auto configured video stream before testing video source type

ArduCopter PID tuning support

Fix overall Palette Window UI

Export color palette in formats that can be directly used by QGC and custom plugins (in addition to the original Json)
Tweak palette export UI