relax SVN archive

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.

Some fixes for the model selection select() function - pipe switching was necessary.

Another fix for the checks in the test_aic_mod_sel_diff_tensor() system test.