Inconsistent filter parameter names in rdbes_download_data() #233

The filtering parameters (filed names) of rdbes_download_data() are difficult to discover and use because their names and expected values do not appear to be consistent with the field names provided in the RDBES data model documentation.

For example, clSpeciesCode and saSpeciesCode require FAO species code when used with rdbes_dowload_data(). However, the corresponding fields in the RDBES data model, CLspeciesCode and SAspeciesCode, are defined to contain AphiaIDs (WoRMS code).

Could the filtering parameters use the same field names and expected values as those defined in the RDBES data model documentation, or could the differences be documented more explicitly?