relax SVN archive

Made the spin_name arg optional in the spin.create() user function.

Started the modification from 'devnull' to tempfiles.

This is as proposed by Edward d'Auvergne to catch the creation of a well formatted and non empty
tensor pdb file and was discussed in a post at:
https://mail.gna.org/public/relax-devel/2008-07/msg00029.html (message ID:
7f080ed10807081248r1f0fda8axd17768bb841efe71@...)

Inverted the population scaling factor in __assemble_scaling_matrix().

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.