relax SVN archive

The position vector is added to the SpinContainer in the load_spins() function.

Created the test_load_protein_asp_atoms_from_pdb() system test.

This tests the loading of all aspartic acid atoms from the single residue in a loaded protein PDB
file.

Bug fix in the Scientific Python PDB object atom_loop() generator method.

The atom name is now returned rather than the element type!

Created the test_load_protein_gly_N_Ca_spins_from_pdb() system test.

This tests the loading of glycine backbone amide N and Ca spins from a loaded protein PDB file.

Added the system test test_load_protein_gly_N_spins_from_pdb().

This tests the loading the glycine backbone amide N spins from a loaded protein PDB file.

Bug fix for the system test of loading the protein backbone amide N spins from a loaded PDB file.

Bug fix for the MoleculeContainer.add_item() method.

The select flag is now set when replacing element 0.

Bug fix for the ResidueContainer.add_item() method.

The select flag is now set when replacing element 0.

Bug fix for the SpinContainer.add_item() method, the select flag is now set when replacing element 0.

Code shift, similar to that of r5443.

Shifted the spin number check (cannot have 2 spin with the same number) and 1st element replacement
(if that SpinContainer is empty) code from generic_fns.spin.create() to the relax data storage
object SpinContainer.add_item() method.