Function `zGetZernike()` does not return information about the wavelength and field position.

[Indranil Sinharoy]

Since the Zernike coefficients are a function of the wavelength and field position, the coefficients do not have any meaning without information about the wavelength and field position in the meta-data (zInfo) portion of the data returned by zGetZernike() function. So, the field position and wavelength should also be returned by the function.