Add support for ArduRover MockLink

Fixed flight widget position.

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

Grouped logging options within General Settings

ArduPilot for configurable mavlink stream rates

Updated MAVLink to handle video stream types (auto discovery)

ArduPilot option to not start mavlink streams

Enable/Disable based on fixed base position

Add support for specifying fixed RTK base position

Added support for qgcRebootRequired Fact meta data value.

Fixed the core MAVLink receiver. Among other things, it wasn't accounting for fragmented messages.
Fixed code that monitors messages received (and lost)
Added a section within the MAVLink panel to show the current status (for the current vehicle)
Remove some old, unused exposed interfaces

Add new Help page under Settings

Show the link indicator in the tool bar if two or more links are connected and at least one of them is a high latency link.
Show in the link indicator if a link is inactive.

This setting enables/disables the LinkIndicator toolbar in which the primary link can be chosen.

Automated preflight checklist: Initial commit. Note that this requires an autopilot firmware that writes the respective health flags in the SYS_STATUS mavlink message

All settings wired and persistent
Cleanup non Airmap builds