(Adds byline, story unchanged) LOS ANGELES (TheWrap.com) - Chemistry, Walter White said in the first episode of "Breaking Bad," is the study of change. And with Sunday's start of the show's fifth and final season, everything has changed for "Breaking Bad" except its brilliant mix of character-driven drama, science-inspired set pieces and cave-dark comedy. Some of the most volatile characters this time around weren't even in that first episode. And the ones that were have turned into different people: Walt (Bryan Cranston) has nearly completed his long-promised transformation from Mr. ...