relax SVN archive

Shifted and renamed the XML module.

Shifted the xml import statements.

The PipeContainer __repr__() and is_empty() methods can now automatically skip new class methods.

The Prototype.__deepcopy__() method can now automatically skip any new class methods.

Fix for the prototype __deepcopy__ method.

Fixes for the PipeContainer methods.

Shifted the generic_fns.xml_data_pipe.write() fn to the PipeContainer.xml_write() method.

Updates to many docstrings.

Added a 'desc' attribute to the pipe XML element.

Made the diff_tensor XML element optional, as the object may not always exist.