relax SVN archive

Created a branch for modifying how relax handles multiple structures verses multiple models.

Currently relax handles models or ensembles of the same molecule verses different molecules very
poorly. This branch is for introducing massive changes to the PDB and structure reading and
handling.

The combine_models flag is now effective in the load_spins() function.

Created a new arg 'combine_models' to the structure.load_spins() user function.

This will allow spins to be extracted separately for each model in an ensemble or for only one set
of spins for all structures.

Another bug fix for the load_pdb() internal structure object method.

This was found by the lactose N-state model system test. The __fill_object_from_pdb() method was
not being called properly and when loading multiple PDB files containing model information, the
first would contain the atomic information of all files!

Partial bug fix for the lactose N-state model system test.

The bond vector returning function for the internal PDB reader was converting the atom_id to
uppercase. This meant that molecule name corresponding to the file name was not matching!

Fixes for the lactose PDB file reading system tests. The path to the files has changed!

Activated the lactose N-state model system test.

Added a system test script for the lactose N-state analysis using RDCs and PCSs.

Added 10 tag PDB files for the lactose system test.

Added some lactose RDC and PCS data. Note this is randomised and truncated for protection!!!