Yes, it’s been an incredibly dark season of “Mad Men,” but the worst part has been seeing a flaccid Don Draper (Jon Hamm) lazily walking through life. Now that’s all changed — the tormented advertising genius is back on top of his game. Maybe it’s Peggy’s departure, or Michael Ginsberg’s constant one-upmanship, but something has put a fire back in Don’s belly. His bravado was on full display last Sunday; whether in his no-nonsense dismissal of Lane or his stirring and terrifying “I won’t settle for 50 percent of anything,” speech to Dow Chemical. I can’t wait to see how Don’s new attitude plays out as this excellent season wraps up Sunday.