decode_utf8
           This attributes defaults to TRUE.

           While parsing, fields that are valid UTF-8, are automatically set
           to be UTF-8, so that

             $csv->parse ("\xC4\xA8\n");

           results in

             PV("\304\250"\0) [UTF8 "\x{128}"]

           Sometimes it might not be a desired action. To prevent those
           upgrades, set this attribute to false, and the result will be

             PV("\304\250"\0)