relax SVN archive

Fix for the atom_loop() method. The position is now returned as a numpy array.

Atom number are now stored in an array to allow for PDB files with missing atoms.

Deleted 6 unit tests for functions which will not be implemented yet.

Wrote the atom_loop() method.

Expanded the Internal.load_pdb() unit test to check all atomic information.

Bug fix for the load_pdb() method, the Structure_container.model variable is now set.

The Structure_container.model variable is now initialised (to None).

Renamed __generate_object_from_pdb() to __fill_object_from_pdb() and changed its behaviour.

The method no longer returns a Structure_container instance but simply fills out the one
corresponding to the model.

Wrote a unit test for the Internal.__parse_pdb_record() method.

Fix by renaming of the Structure_container.__init__() method.