relax SVN archive

The references to 'data_type' have been changed to 'param'.

The docstrings for 'set' and 'return_data_name' have been reversed in all user function docstrings.

The user function 'diffusion_tensor.set' has been renamed to 'diffusion_tensor.init'.

The generic function 'diffusion_tensor.set' has been forked into the parameter setting function
'diffusion_tensor.set' and tensor initialisation function 'diffusion_tensor.init'.

A bug has been removed from the 'diffusion_tensor.map_bounds' generic function involving the
returning of parameter specific data.

The functions in the generic 'diffusion_tensor' class have been alphabetically reordered.

The generic function 'value.set' has been extensively rewritten to handle diffusion tensor
parameters.

A new generic function 'value.sort_params' has been added to specifically handle the flexibility of
the user function 'value.set'.

A few bugs in 'specific_fns/jw_mapping.py' and 'specific_fns/model_free.py' have been removed.
These involve the returning of parameter specific data.

The 'RelaxUnknownParamError' error has been expanded.