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

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

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