Give users the ability to remove the topic text and section number.

Original request from DJ Paxton (http://moodle.org/user/view.php?id=90371) to remove 'Topic x' from the toggle and the section number from the section. Custom code supplied through http://moodle.org/mod/forum/discuss.php?d=157548 with a request from Patrick Tierney (http://moodle.org/user/view.php?id=1065347) to have the code added to the main build.