This week’s “Doctor Who” culminates a plot not just from last week, but from the 50th anniversary episode, “Day of the Doctor.” Still, the most important thing in it may be Peter Capaldi’s one-man show, which doubles as a mission statement for The Doctor. And while Clara isn’t in it much, Jenna Coleman does a great turn as her Zygon duplicate. Plus, more Osgood! Host Jason Snell with Lauren Snell.