Disable ADC debug output
Autotune phase changes.

Add an additional phase to allow previous pid settings to be restored,
in flight, after auto tuning.
Replace unused runtime warning beep code with autotune beep code.
If auto tune was used, and the user landed the aircraft, then before it
is used again it must be reset.

Otherwise the first flip of the switch would start the next phase which
could mean that PID settings were restored.