Add persistRcValuesButt to allow mappings to be persisted outside the
calibration mode; cleanup const params in param dataq model;  add some
debug for mapping problems

Cleanup pending items tree completely when we receive an update

Config space

fixed runtime error with a typedef:
QObject::connect: Cannot queue arguments of type
'QSerialPort::SerialPortError'
(Make sure 'QSerialPort::SerialPortError' is registered using
qRegisterMetaType().)

Checkpoint: RC calibration much better / operation, can use UI tweaks. Airframe config in, but not operational and still very functional / ugly.

Config tweaks

Refactored QGCUASParamManager so that it is no longer a widget and contains no View code

Avoid re-requesting paramlist when opening new param widget; Fix widget promotion