relax SVN archive

The units in the return_data_desc() now come from the return_unit() method.

Shifted the spin specific object name and descriptions into the specific code.

Added a few more specific functions to get_specific_fn().

The spin specific relaxation data structures are now properly initialised.

Added the spin specific relaxation data objects to the model-free data_names() return value.

Converted the global_flag arg to a keyword arg in get_data_names().

Partial fix for bug #11860 (http://gna.org/bugs/?11860).

The partial fix was to change the force flag to a bool in the diff_tensor_pdb.py sample script.

Updated the data_names() and data_init() methods to include more of the model-free data pipe objects.

Added spin object descriptions to the XML elements.

The SpinContainer XML elements are now sorted as in the relax 1.2 results file.