[NRKTV] Add support for downloading series (playlist)

[oddstr13]

• I've verified and I assure that I'm running youtube-dl 2016.12.22

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• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
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• Series: http://tv.nrksuper.no/serie/wallace-og-gromit
• Series: https://tv.nrk.no/serie/skam
• Series: https://tv.nrk.no/serie/oppfinneren
• Series: https://tv.nrk.no/serie/nytt-paa-nytt
• Series: https://tv.nrk.no/serie/broedrene-dal-og-professor-droevels-hemmelighet
• Series extras: https://tv.nrk.no/extramaterial/skam
• Episode listing (Series season): https://tv.nrk.no/program/Episodes/skam/70522
• Episode listing (Series season): https://tv.nrk.no/program/Episodes/game-of-thrones/27567
• Episode listing (Series season): https://tv.nrk.no/program/Episodes/game-of-thrones/75362
• Episode listing (Series season): https://tv.nrk.no/program/Episodes/game-of-thrones/86355

Some series/episodes are available world wide until end of time. Some have time and or geo restrictions.

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Description of your issue, suggested solution and other information

Add support for downloading all (available), or a subset of episodes of a TV Series from the domains tv.nrk.no and tv.nrksuper.no.

[oddstr13]

Episodes listing download is now working. https://tv.nrk.no/program/Episodes/gubben-og-katten/74302
Full series download does not work. https://tv.nrk.no/serie/gubben-og-katten

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Season and Episode number information not properly populated in format string;

• Format: /mnt/Media/youtube-dl/%(extractor)s/series/%(series)s/%(season_number)s - %(season)s/[%(id)s] - %(episode_number)s - %(episode)s %(title)s/[%(id)s] - %(title)s.%(ext)s
• Output: /mnt/Media/youtube-dl/NRK/series/Gubben og katten/NA - NA/[OBUI53006605AA] - NA - 6_6 Gubben og katten og nissemaskinen 6_6/[OBUI53006605AA] - Gubben og katten og nissemaskinen 6_6.mp4
• Expected output: /mnt/Media/youtube-dl/NRK/series/Gubben og katten/2 - Sesong 2/[OBUI53006605AA] - 6 - 6_6 Gubben og katten og nissemaskinen 6_6/[OBUI53006605AA] - Gubben og katten og nissemaskinen 6_6.mp4 or somewhere along those lines.

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Season and episode number can be extracted from a couple locations in the json meta file, in addition to the data.episodeNumberOrDate.

• data.episodeNumberOrDate
  • "5:6"
  • "01.01.2017"
• data.scoresStatistics.springStreamStream
  • "programspiller/odm/barn/gubben-og-katten/s02e05.gubben-og-katten-og-nissemaskinen.OBUI53006505"
  • "programspiller/odm/nyheter/dagsrevyen/s201701e0101.dagsrevyen.NNFA19010117"
• data.relativeOriginUrl
  • "serie/gubben-og-katten/OBUI53006505/sesong-2/episode-5"
  • "serie/dagsrevyen/NNFA19010117/01-01-2017"

I have not extensively checked different shows to see if they follow the same pattern, but I've noticed the season-x/episode-y part of the URL on several occasions over time. The statistics one I found now, after having a look at the json file dumped by youtube-dl. From the few samples I've had a look at, it seems to follow a rather strict sxxeyy structure.
Not sure which is best overall, but S201701 E0101 is sortable by name giving chronological order, which is always a good thing. 01.01.2017 or 01-01-2017 not so much, as that is %d-%m-%Y... or is it %m-%d-%Y? I always mix those together.

[dstftw]

Cherry-picked, thanks.