Added plotting function to graphics library which is native C++, so
refactored the graphics source file to allow that, consequently adapted
the hwconfig header files to be included also in C++ sources.
Propagated compile flags also to C++ sources, including asan what was
previously disabled for C++ compilation units.
TG-81
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
Fix a bug where the signature of the battery draw function was not
present, causing a build error. Now the battery size and position is
screen size independent and should work for all layouts.