relax SVN archive

Bug fix for a very long standing bug!

This is the 'population' N-state model bug whereby the last probability, which is not a parameter,
has a negative value. The constraint was not being scaled! So the constraint was actually a
probability 0 <= pN <= 100!!!

Added 3 system tests for the correct loading of XH bond vectors into the spin containers.

This catches the previously fixed model looping bug.

Bug fix for when structural models are loaded out of order.

Now the API generator method model_loop() is being used by the scientific python and internal
structural objects. The bond vectors and atomic positions are now loaded into the spin containers
in correct numerical model order.

Updates to the 'population' N-state model system test script.

Created the d2func_population() Hessian target function for the N-state model.

This may either be buggy or too sparse to run Newton optimisation well!

Updated and corrected all the Hessian method docstrings.

Bug fix for the N-state model 'fixed' and 'population' models.

If too many tensors are initialised in comparison to PCS and RDC alignments, then the parameter
vector or parameter number was not being correctly assembled. The cdp.align_ids is now being used
to validate all setups.

Bug fix for the 'population' N-state model optimisation.

Constraints must be used at all times for this to work!!!

Another fix for the huge bug identified in r11163.

This is for the PCS part - this was also using equal weights for all states set to pN!

Another fix for _update_model().

This was introduced in the last change. The alignment tensors are only updated if alignment data
is loaded.