relax SVN archive

Expansion of the docstring of the unit test of maths_fns.n_state_model.func().

Wrote a unit test for the maths_fns.n_state_model.func() optimisation target function.

Bug fix for the maths_fns.n_state_model.func() optimisation target function.

The back-calculated the reduced tensor structure is now being reset to zero at each call. Because
of the sum, it was just getting bigger and bigger.

Bug fix for the maths_fns.n_state_model.func() optimisation target function.

The probability of state N was not being caught and calculated from the others.

Fixes for the default_value() method.

The value.set() user function now works for the N-state model.

Fix for the return_data_name() method.

The probability structure is called 'probs'. The docstring has been updated as well to reflect the
real object names.

Bug fix for the 'betac' parameter in the return_data_name() method.

There are less characters in 'beta' than 'alpha'!

Rewrote the return_data_name() method to handle the N-state model parameters.

Wrote the N-state model set_doc() method (which is just a docstring for the user functions).

Added the N-state model docstrings to the value.set() user function.