Eliminated a lot of unused code from the pipe_control.align_tensor module.
This includes the functions data_names(), default_value(), map_bounds(), map_labels(),
return_conversion_factor(), return_data_name() and return_units() as well as the unused and very old
user function documentation __default_value_prompt_doc__, __return_data_name_prompt_doc__ and
__set_prompt_doc__. These are all remnants from the origin of the module - the copying of the
diffusion_tensor module. But they have never been used.
