It may be Star Wars Day everywhere else, but tonight in Harvard Square, it's Zombie Day: Anyone looking to catch a sneak preview of George A. Romero's Survival of the Dead would do well to shuffle down to the Brattle Theatre tonight. In anticipation of its May 28 theatrical release (note that you can already catch this sixth installment of the "Dead" series in a number of places online), the Grandfather of the Zombie Film will be on hand to introduce his movie -- and if that isn't enough to peel you zombie fans off the couch, I'm not sure anything will.