relax SVN archive

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.

Added the import of the generic_fns.diffusion_tensor module.

Another fix for the params arg unit test for the diffusion_tensor.init() user function.

Fixed the params arg unit test for the diffusion_tensor.init() user function.

Added a number of tuples of floats of different sizes for the user function argument unit tests.

Implemented the test of diffusion_tensor.copy(), that both arguments cannot be None.

A unit test for this has also been added.

Bug fix for the diffusion_tensor.copy() user function.

The pipes can be None.

Implemented all the arg unit tests for the diffusion_tensor.copy() user function.