A small change to a generic_fns.molecule.display() unit test.
Added 2 unit tests for the generic_fns.molecule.display() function.
Fixed a problem in the 'test_delete_all()' unit test.
Implemented the generic_fns.molecule.delete() function.
Added a unit test for the failure of the generic_fns.molecule.delete() function.
Added a unit test for the deletion of all molecules.
Added a unit test for the generic_fns.molecule.delete() function.
A few changes to the residue.copy() user function RelaxError messages.
Created the molecule.copy() user function interface.
Added two more unit tests for the generic_fns.molecule.copy() function.