relax SVN archive

The domain user function arg spin_id can now be set to None.

This is useful if the domains are not associated with spins.

Updated the scientific PDB reader atom_loop() method to match the changes to the API.

Fixes for all of the unit tests of the compile_2nd_matrix*() frame order functions.

Fix for the test_atom_loop_spin_selection2() unit test.

The atom loop is now a little different, and the position information is now always a rank-2 array.

Fix for the calls to generic_fns.align_tensor.get_tensor_index().

The arguments have been changed.

Fix for the structure.get_pos user function.

This has been updated for the atom_loop() structural API method change.

Fix for some unit tests using the atom_loop() structural API method incorrectly.

The model_num_flag arg no longer exists.

Missing import.

The frame order specific API method sim_return_param() now matches the API.

The structural API atom_loop() methods now all have the model_num_flag arg dropped.