relax SVN archive

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.

Fix for the test_read_results_1_2() system test.

Changed the variables initialised by the PipeContainer.__init__() method.

Many are no longer initialised and the hybrid_pipes dictionary has been converted to a list.

Added the structural information to the XML results file.

Docstring improvements.

The hybrid element is no longer returned.

Shifted the hybridisation info from the global element to its own element.

Shifted all the variables of PipeContainer into the 'global' element.