By DAN VINTON If there’s one thing The Last Airbender does well, it proves any mystique surrounding M. Night Shaymalan is gone. With this coffin-bound nail, all residual goodwill The Sixth Sense director retained from followup successes like Unbreakable, Signs and even the creepy but fatally flawed The Village has been throttled by his is own hands. Shaymalan’s latest, (based on the 2005-2008 Nickelodeon cartoon series I’ve never seen), builds a likable, tactile, genuinely fascinating and lushly art-directed world of …