relax SVN archive

Fix for the spectral density calculation system test.

The proton type is now set.

Added some missing RelaxError imports.

Improved testing in the spectral density mapping calculate() method.

Fixed the setup of the maths_fns.jw_mapping.Mapping object.

Converted the select() method docstring to epydoc format.

Removed some debugging code.

Reintroduced the modsel_pipe arg to the select() function.

Reintroduced the modsel_pipe arg to the model_selection() user function (the deleted modsel_run).

Modified the test_aic_mod_sel_diff_tensor() system test.

The model selection pipe will be created by the model_selection() use function, it doesn't need to
be precreated!

Converted the model-free model_statistics() method to the new relax design.