relax SVN archive

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.

Removed the useless molecule user functions remaining from the copy from 'prompt/sequence.py'.