relax SVN archive

The minimisation code now uses the scaling matrix.

Missing import fix.

Unscaled the parameter vector after optimisation.

Made some more use of the scaling matrix.

Made diagonal scaling optional.

Wrote the __assemble_scaling_matrix() method for creating a scaling matrix for the N-state model.

Fix for the counting of header lines. The residue or spin number need not be supplied.

Updated the param_num() method to take the various models into account.

Redesigned the disassemble_param_vector() method for the multiple N-state model types.

Docstring fixes.