Allow user to set the q basis after an optic is added to the opt.

In response to Keiko needing to set the q basis of an optic after creating the opt:

I copy paste a part using setFrontBasis giving me an error. I now think I used in a wrong way (the last sentence, opt can not be changed), but I am not sure how to change opt.optic in a different way.
%  opt = optFP;
%  sn1 = getSerialNum(opt, 'EX');
%  obj1 = opt.optic{sn1};
%   z = 5;
%  opt.optic{sn1} = setFrontBasis(obj1, z);