relax SVN archive

Docstring fix.

Converted the generic_fns.diffusion_tensor.init() function to the new relax design.

Updated the copyright notices.

Fixed the prompt modules which were importing the Diffusion_tensor class.

Converted all the Diffusion_tensor methods into module functions.

The class no longer exists.

Removed an unused import of pi.

Shifted all the calc_* diffusion tensor functions from generic_fns to data.

This is to break a fatal circular import problem!!!

Removed all of the generic_fns class instances from the relax namespace.

All these class methods will be converted to module functions.

Removed the placement of the Diffusion_tensor class instance into generic_fns.

Wrote two unit tests for the diffusion tensor initialisation.

One is for bad angular units, the other is for setting a spherical tensor.