switched spm_srxl.c to C++ compilation
Correctly set budget for half-duplex writes
Tidy PACKED and other externalities
disable SRXL2 on IOMCU and softserial - SRXL2 is a serial half-duplex protocol-only
fixed buffer overrun in SRXL2 parser
fix bugs in decoder sketch and allow output to SITL
add support for temperature, battery voltage, battery current, flight pack
altitiude, airspeed, attitude and compass, GPS, ESC telemetry based on BLHeli
status messages and QOS packets.
refactor into AP_Telemetry
conditionally compile based on HAL_MINIMIZE_FEATURES
don't initialize spektrum telemetry if there is no RC uart