relax SVN archive

Fixes for the unit tests of the spin and molecule loops when no data is present.

Fixed the unit test of the residue loop with no data pipes present.

The unittest framework couldn't handle the generator function, so an intermediary function was
created!

Added a unit test for the proper operation of the residue loop when no data pipe is present.

Added the generic_fns.pipes.test() function to the molecule, residue, and spin loop functions.

Created the test() function for testing the existence of the current or given data pipe.

Added a unit test for the proper operation of the residue loop when no data is present.

Added a unit test for the proper operation of the molecule loop when no data is present.

Added a unit test for the proper operation of the spin loop when no data is present.

Added a unit test for the generic_fns.selection.count_spins() function, for when there is no data.

Added a unit test for the generic_fns.selection.count_spins() function.