Added implementation of the M17 4FSK demodulator, including clock
recovery, phase detection, and quantization algorithms.
A testsuite is also included to do regression testing against a
reference baseband pre-generated and the corresponding reference
bitstream.
A 1% BER is still present due to a fault likely in the RRC filtering,
since the eye diagram of the filtered stream is bad.
TG-81
Niccolò Izzo