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 

when param widget is loaded we only want to re-request the whole param list if we don't already have one