Fixed display of MTF plot and added knife-edge img
Fixed display of MTF plot and added knife-edge img

I needed to do it step by step with simple plotting commands :) Now it
shows the correct horizontal and vertical lines in the plot.
Also added knife-edge image to have a third synthetic image for
analyzing the MTF properties.

habi/GlobalDiagnostiX,habi/GlobalDiagnostiX,habi/GlobalDiagnostiX