Time travel movies are tricky, but director Doug Liman has delivered a science-fiction gem with “Edge of Tomorrow,” a fast-paced, action-heavy affair that plays like a mash up of “Groundhog Day” and “War of the Worlds.”  The picture is set in a near future where frightening, tentacular creatures have launched an all-out assault on Earth. Just when it looks like the alien beings are invincible, Sgt. Rita Vrataski (Emily Blunt) leads humanity to an impressive victory using a heavily armed exoskeleton.