relax SVN archive

Alphabetical ordering of methods, and shifting of the spheroid to ellipsoid checks into a separate method.

Renamed test_init_spheroid_as_ellipsoid() to test_init_prolate_spheroid_as_ellipsoid().

The print outs of the system test have been slightly improved.

The tensor is first twisted before rotating to PDB frame in the spheroid diffusion tensor system tests.

The twisting rotation was not being correctly performed.

Fix for the spheroid diffusion tensors for a recently introduced bug.

The oblate and prolate check was failing as the 'spheroid_type' variable was set to None after a
call to diffusion_tensor.init(). 'spheroid_type' is now automatically updated if Da is changed.

Added 6 system tests for the initialisation of the prolate spheroid diffusion tensor.

The hardcoded variables in get_spheroid() are now keyword args.

Some small cosmetic changes to the spheroid diffusion tensor system tests.

For some reason, the diffusion tensor PDB file for the oblate tensor now has a slight rotation.

This rotation is about the unique axis of the tensor, so this gives a different PDB file, but the
representation is the same.

Fix for the creation of the oblate spheroid geometric object PDB file.

The x and z axes need to be swapped now for the oblate tensor.

Some more fixes for handling the diffusion tensor data structure 'spheroid_type' variable properly.