Create a Zernike mode

Create a Zernike mode based on the indices (u,v) at the position rho and
theta from the origin of the grid. The positions rho and theta can
either be a scalar or an array (not matrix a type).
Test the WFG: Zernike

This file is indented to debug the WFG algorithm. It will plot the
Zernike mode specified in the code, it is messy code as is made for
debugging purposes only. You can see the usage  of the zernike function.