fixed bug for member only forum;
fixed bug:list private topics as guest when call get_latest_topic method.

Signed-off-by: TomWu <phperwuhan@gmail.com>
fixed a php code bug when call get_latest_topic.

Signed-off-by: TomWu <phperwuhan@gmail.com>
updated banner feature and fixed related issue.

Signed-off-by: TomWu <phperwuhan@gmail.com>