There’s a commonly used phrase these days, “Jumping the Shark,” used to pinpoint the moment when a TV series starts to lose its way, big-time. (Example: The final seasons of Dexter.) But there ought to be a name for the reverse, when a show suddenly finds its mojo and gets significantly even better. That’s been the case, all this season, with Bates Motel, which, as it gets closer to its rendezvous with the familiar plot line from Psycho, has gotten amazingly clever, creep