Fix formatting and PHP notices in include/conversation
Fix formatting and PHP notices in include/conversation

- Remove unused $nickname variable
- Remove unused $comment variable
- Use defaults() in get_responses() to check for array key existence

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