Test FFTmagnitude() and FFTpower() against Python/Numpy

EDIT: I had a moment where I was worried about how FFTmagnitude() calculated its values, but I was reassured all is well by calculating identical values with numpy and matplotlib. I added these comparisons as new tests to ensure FftSharp output remains identical to numpy.

I added new tests to confirm the output of this Python code is identical to the equivalent calls using FftSharp:

FftSharp/dev/python/fft.py

Lines 41 to 50 in bbe1289

    
           sampleRate = 48_000 
        
           samplePeriod = 1.0 / sampleRate 
        
           N = len(values) 
        
           fft = np.fft.fft(values) 
        
           fftFreq = np.fft.fftfreq(N, samplePeriod) 
        
           fftReal = np.fft.rfft(values) 
        
           fftMag = np.abs(fftReal) * 2 / N 
        
           fftMag[0] = np.abs(fftReal[0]) / N  # special case for DC 
        
           fftDB = 20 * np.log10(fftMag)

	sampleRate = 48_000
	samplePeriod = 1.0 / sampleRate

	N = len(values)
	fft = np.fft.fft(values)
	fftFreq = np.fft.fftfreq(N, samplePeriod)
	fftReal = np.fft.rfft(values)
	fftMag = np.abs(fftReal) * 2 / N
	fftMag[0] = np.abs(fftReal[0]) / N # special case for DC
	fftDB = 20 * np.log10(fftMag)