added complex_t
moved complex number helpers to complex.rsh
put header guards to complex.rsh
moved ema code to ema.rsh
moved phasor code to phasor.rsh
cleaned up ema code, introduced overloadable filter interface
moved ddc to ddc.rsh, made filter order less flexible
moved fmd code to fmd.rsh
split constants, state, modes, scanline estimator and calibration detector