relax SVN archive

Created the molecule.copy() user function interface.

Added two more unit tests for the generic_fns.molecule.copy() function.

Added a unit test to test the failure of copying molecule data to a non-existent data pipe.

Wrote the generic_fns.molecule.copy() function.

A few more fixes to the 'return_molecule()' function.

Another fix for the 'return_molecule()' function.

Modified the 'generic_fns.residue.copy()' function to work with the modified 'return_molecule()' fn.

Five unit test were failing due to the previous commit. This was because of a problem in
'generic_fns.residue.copy()' that wasn't previously detected.

Added the 'return_single_molecule_info()' function and fixed the 'return_molecule()' function.

The 'return_molecule()' function was returning a molecule container when no molecule selection was
given. Now None is returned.

Added a unit test for the copying of the molecule data between different data pipes.

Renamed the user function 'molecule.add()' to 'molecule.create()' in the redesign doc.