Stickies a topic - toggles between sticky and normal.

• Requires the make_sticky permission.
• Requires the enableStickyTopics setting to be set
• Expects the topic to be in $topic global variable
• Requires a valid session ID in the querystring
• Adds an entry to the moderation log (if_enabled).
• When done, sends the user back to the topic.
• Accessed via ?action=sticky.