MTF.py now does polynomial fits.
MTF.py now does polynomial fits.

Introduced function based on code from http://is.gd/q18xED to perform a polynomial fit
Plotting the polynomial fit in a fourth row of the plot, so we can calculate the MTF @ Nyquist from this

habi/GlobalDiagnostiX,habi/GlobalDiagnostiX,habi/GlobalDiagnostiX