relax SVN archive

Bug fix for the loading of multiple files.

Each time a new file was loaded, all its atoms would be appended to all other presently loaded
structures. This would cause large slow downs of the atom_loop() function, and a few other
problems. Now structures are referenced by structure index rather than model number.

Added a script for consistency_tests system testing.

This one is, basically, a copy of the sample script. Changes are thus needed for it to work as a
system test script.

Added the use of a script for consistency_tests system testing.

Changed the test suite reference value for eta so the test passes after the equation modification.

This change follows the one for r6665 (http://svn.gna.org/viewcvs/relax?rev=6665&view=rev) and had
already been made on the 1.2 line, but was also needed on the 1.3 line. See r6611
(http://svn.gna.org/viewcvs/relax?rev=6611&view=rev) for details.

Bug fix for the load_spins() function.

Molecule, residue, and spin information can be missing and the function still work.

Some changes towards the new design.

The script doesn't work yet and will be introduced into the test suite for further debugging.

The internal PDB object atom_loop() method now can return the average atom properties, if asked.

The internal PDB object atom_loop() method now recognises the ave arg, but does nothing when True.

Added the str_id arg to the Scientific PDB object atom_loop() method.

Added the ave arg to all atom_loop() methods to allow just the average properties to be returned.