relax SVN archive

Updated the docstring of 'generic_fns.pipes.create' to be in Epydoc format.

Updated the import statements, removing many unused imports.

Added a docstring to the Test_diff_tensor class.

Removed the ability for stand alone execution of the diffusion tensor data structure unit tests.

Stand alone execution is unnecessary as the command:

$ ./unit_test_runner.py data/test_diff_tensor.py

will run the tests.

Three things have been changed. Firstly the system path modifications have been removed. Secondly
the 'if __name__ == "__main__":' block has been deleted. Finally the 'svn:executable' property has
been removed from the repository.

Added the 'generic_fns/' directory to the unit test hierarchy.

Deleted the Pipes class and converted all its methods into module functions.

Updated the data model redesign document to say that point 8 of the preparation is complete.

Renamed 'run' to 'pipe' in the 'generic_fns.runs' module.

The file 'generic_fns/run.py' was renamed to 'generic_fns/pipe.py' and all instances of 'run'
renamed to 'pipe'.

Renamed 'run' to 'pipe' in the 'run' user function class.

The file 'prompt/run.py' was renamed to 'prompt/pipe.py' and all instances of 'run' renamed to
'pipe'. The placing of the user function class into the interpreter namespace was also updated.
The docstrings of all the user functions where modified to use the new terminology.

Updated the 'data_model_redesign' document to state that the redesign of 'self.relax.data' is complete.