relax SVN archive

Added two unit tests for the generic_fns.selection.return_molecule() function.

Also made the function fail properly when no data pipe exists.

Added another unit test for the generic_fns.selection.return_residue() function.

Added a test for the failure of the generic_fns.selection.return_residue() function.

This tests the failure of asking for a non-existent data pipe and the function has been fixed to
fail appropriately.

A large number of changes to make the residue.copy() user function fully functional.

Now residue data can be copied within a single molecule, between molecules, and between data pipes.

More unit tests for the generic_fns.residue.copy() function.

The current test was renamed. Two new tests were added for copying between molecules and copying
between data pipes.

Spelling correction.

Alphabetical arrangement of the residue user functions.

Added the rudimentary beginnings of the molecule user function class.

Implemented the generic_fns.residue.renumber() function and fixed its unit tests.

Created the generic_fns.residue.rename() function and fixed the corresponding unit tests.