BBC America, like the BBC itself, has outdone itself celebrating the golden anniversary of Doctor Who, which premiered in England on this date in 1963. That even goes to Graham Norton’s talk show, which has been positively delightful this season. Tonight, his guests include the two most recent actors, as of yesterday, anyway, to have played The Doctor: David Tennant and Matt Smith, the Tenth and Eleventh Doctors, respectively. On the same couch, at the same time. Though time, to a Doctor Who fan, is entirely relative…