This was leftover from a problem I was having with virtual slots

Allows for UI unit tests to be written:
- Ability to respond to expected message boxes
- Ability to fail test if unexpected message boxes occurs

Allows you to run a single unit test from the command line

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

Destroyed signal must have been working incorrectly in the past.

Centralize all connecting and disconnecting of links through
LinkManager::[Connect|Disconnect]Link api. Connect/Disconnect no longer
allowed through LinkInterface. This allows creation of new
LinkManager::setConnections[Suspended|Allowed] methods to disallow
connections as needed.

This allows you to determine if full parameter list is ready if you
missed the parameterListUpToDate signal.

This allows you to determine if full parameter list is ready if you
missed the parameterListUpToDate signal.

Handy for testing without a real board

This test is too flaky to run in TeamCity reliably.

Specifically:
- Channel reversing
- Incorrect usage of function and channel index

- Also corrected system/component id usage
- Switched to new Qt5 connect api

Also uses new min/max/invalid widget display

- Updated to use RCChannelWidget
- Removed attitude control widgets
- Previous calibration values now shown when not actively calibrating