Moving methods from MainWindow to QGCApplication so that more things
can run without a window. Helpful for testing.

Emitting signal beforehand can lead to subtle bugs where code expects
value to be updated and it is not.

Starting point for real implementation

No longer needed with move to summary page qml

Summary page is also the launching spot for the setup screens. No more
left hand set of buttons.

This prevents mavlink signals from being emitted after link is
disconnected

When using DeleteOnClose with a QQuickWidget, the shutdown sequence
causes the MainWindow destructor loop back onto itself.

- properties now hand off of main “autopilot” object in qml
- Added support for summary items through qml