WFS update, and added function for rectangular setups in the main

Increased the readability of mainWFS.py.
Normalized the intensity distribution and the lensletCentx/y.
Added support length for FFT in the parameters for the sensors.
Added function in main to handle rectangular lenslet configurations.
 
@forcaeluz  I don't think I'm using this data am I?
But I'm not really grasping what is happening in all the code with a quick look.