UAS may be around at constructor time

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.

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

Plus a large number of other changes to allow for orderly shutdown of
objects without crashes or asserts. This is need for unit tests to
create/delete global state around every test.

- allow unit tests to use QGCApplication
- clear global singletons for each unit test run