relax SVN archive

Fixes for the N-state model target function gradient and Hessian for the data structure changes.

The unit vector data structure is no longer a pure numpy array but a mixed list and array structure
to handle pseudo-atoms.

Fix for the N_state_model.test_stereochem_analysis system test for the pseudo-atom handling.

An interatomic distance file is now used to explicitly set up all distances.

The pipe_control.rdc.q_factors() function now properly handles pseudo-atoms.

If pseudo-atoms are present, then 2Da^2(4 + 3R)/5 normalised Q factor is skipped.

The N-state model specific check_rdcs() function now properly handles pseudo-atoms.

The stereochemistry auto-analysis can now accept a file of interatomic distances.

This is for better pseudo-atom support.

Updated the value checking for the N_state_model.test_absolute_rdc_menthol system test.

The pseudo-atoms are now properly handled so the result is now much better.

The interatom.unit_vectors user function now calculates the unit vectors for deselected containers.

This is useful for pseudo-atom handling where the interatomic containers to the pseudo-atom members
have already been deselected.

Renamed the interatomic_loop() function 'selected' argument to 'skip_desel'.

This is to match the spin_loop() function arguments.

Updated the menthol long range RDC data file to include pseudo-atom member distances.

An RDC error of 0.0 will now deselect the corresponding interatomic data container.

This can be used for simpler pseudo-atom handling.