Generator: addressed some shortcomings with the copy constructor of the `Generator` class.
Generator: addressed some shortcomings with the copy constructor of the `Generator` class.

nickerso/libcellml,hsorby/libcellml,cellml/libcellml,cellml/libcellml,MichaelClerx/libcellml,nickerso/libcellml,MichaelClerx/libcellml,hsorby/libcellml,MichaelClerx/libcellml,nickerso/libcellml,nickerso/libcellml,hsorby/libcellml,cellml/libcellml,hsorby/libcellml,cellml/libcellml