Rewrite of the FrSkyX code to support both v1 and v2.1.0 with FCC and LBT.
FrSky v1 accessible as usual
FrSky v2.1.0 accessible through the protocol 64=FrSkyX2 with the same subprotocols as v1
The LBT feature is now fully implemented on the TX and turned on for both v1 LBT and v2.1.0 LBT.
For v2.1.0, to access the bind functions Telem=on/off, CH1-8/9-16 and bidirectional SPort (SxR setup for example), you need to update OpenTX to the latest 2.3.8 nightly (not available yet).