relax SVN archive

Fix for the atom_loop() method needed because of the load_pdb() changes.

Fix for the test_load_pdb() unit test.

Fixed some references to os.path.

Added the missing struct_index to load_pdb().

Redesigned the internal and Scientific load_pdb() methods.

An auxiliary method __add_struct() was created for looking after the structure additions.

Added the NMR model number to the collection of structural attributes stored as lists.

The load_pdb() structural method now accepts the struct_index arg.

This is passed in by from_xml() to place the structure in the correct position.

Modified from_xml() to handle multiple loaded structures.

Modified the structural API base class __init__() method.

This is to prepare for the tidying up of the structural object to better handle multiple structures.

Propagation of the results file directory all the way through to the structure reading code.