Replace mb_convert_encoding with html_entity_decode for feed item title conversion
Replace mb_convert_encoding with html_entity_decode for feed item title conversion

- Prevents already UTF-8 strings to be corrupted

fabrixxm/friendica,fabrixxm/friendica,friendica/friendica,annando/friendica,annando/friendica,tobiasd/friendica,tobiasd/friendica,fabrixxm/friendica,annando/friendica,friendica/friendica,fabrixxm/friendica,tobiasd/friendica,tobiasd/friendica,friendica/friendica,annando/friendica,friendica/friendica,fabrixxm/friendica,tobiasd/friendica,annando/friendica,friendica/friendica