[ticket/9550] Add template event in the footer of view topic pages

Adds a template event to bottom of view topic pages, under the
pagination and quick reply, but prior to any bread crumbs.
http://area51.phpbb.com/phpBB/viewtopic.php?f=111&t=43385
http://tracker.phpbb.com/browse/PHPBB3-9550

PHPBB3-9550