M4 zernike routine

[runabriguglio]

start defining the procedure to compute the Zernike command on M4.

hints:

• may be based on applyFlatCmd, using a passed image (in this way, we produce a differential command, without flattening the current shape --> then we can verify the resulting shape with a differential measurement)
• we need a img2OTTimg and viceversa to ajust and crop the Zernike shape wrt M4 segments
  img2OTTimg may be based on OTT parameters (opt_beam.parabola and opt_beam.rotator)