The sixth and final season of Downton Abbey is almost here and we're pretty devastated to see it go (Bates and Anna! Mr. Carson and Mrs. Hughes! The Dowager Duchess and her on-point bon mots! It's all too much to bear.). And as we tune in to pick up where we left off with our favorite upstairs and downstairs characters on Sunday night (January 3, 9 P.M. ET/8 P.M. CT, on PBS), we're also excited to see the incredible costumes. Namely, those of our fave It Girl from another era Lady Mary, who...