SEASON PREMIERE: This super-long-running BBC series returns for yet another year, but not quite yet another Doctor. Peter Capaldi returns as this latest incarnation of the time-traveling Time Lord, although Capaldi has let it be known this is his last year, before the Doctor regenerates into another new form. It’s the last season, too, for Steven Moffat, who has done such a brilliant job reinventing this series the past seven years. Meanwhile, Doctor Who has a new companion this year, an a