Configuration string, space-delimited list of options, exactly as
      in original Tidy@s command-line or in Tidy@s configuration file.
      Not all options of original Tidy will work, due to obvious reasons,
      unsupported options will be silently ignored, so you may read your
      favorite Tidy@s configuration file by file_to_string function and
      pass it to tidy_list_errors. For more datails, see
      tidy_html.
      