relax SVN archive

Added an ID string to load_spins() to fix a bug in the return_residue() and return_spin() calls.

Bug fix for the test_pdb() system test.

Expanded the data structure testing in the system test for loading of a sequence from a PDB file.

Buf fix for the system test for the loading of a sequence from a PDB file.

Only 12 residues exist in the PDB file.

Bug fix in the load_spins() function.

Renamed incorrectly named variables.

Modified load_spins() to handle a single molecule with no name.

Added some missing imports.

Buf fix for the system test for the loading of a sequence from a PDB file.

The N atom was incorrectly specified.

Added the atom_id keyword to the Scientific Python PDB data object atom_loop() method.

Fixes and expansion of the system test for the loading of a sequence from a PDB file.