flightgear hil: correct scaling of pressure for mavlink message and remove indicated airspeed from flightgear protocol, commit requires flightgear protocol update

This commit disabled RC RAW signal callback.

Fixed race issues in config upload, tested to be reliable now - board startup scripts now need the other half of testing

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

reduce serial link logging; clear transmit buffer on disconnect

reduce serial link logging; clear transmit buffer on disconnect

Another change for issue #3, SerialLink::getCurrentPortS() should now return consistant results on Windows to match linux and OSX

Have settings loaded/stored correctly for all joysticks based on their UAS type and autopilot type. Switching between UASes doesn't work right yet, however.

Addition of requestReset to LinkInterface, to allow MavLinkProtocol to detect when connected, but at the wrong baud rate, request a reset.

Changed many functions in the abstract *Link classes to be const. This facilitates setting other functions as const. The metadata for specific links are reset when the links are added.