Log Message:
youtube-dl: Update net/youtube-dl to 20171210

Changes:
2017.12.10
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Core
+ [utils] Add sami mimetype to mimetype2ext

Extractors
* [culturebox] Improve video id extraction (#14947)
* [twitter] Improve extraction (#14197)
+ [udemy] Extract more HLS formats
* [udemy] Improve course id extraction (#14938)
+ [stretchinternet] Add support for portal.stretchinternet.com (#14576)
* [ellentube] Fix extraction (#14407, #14570)
+ [raiplay:playlist] Add support for playlists (#14563)
* [sonyliv] Bypass geo restriction
* [sonyliv] Extract higher quality formats (#14922)
* [fox] Extract subtitles
+ [fox] Add support for Adobe Pass authentication (#14205, #14489)
- [dailymotion:cloud] Remove extractor (#6794)
* [xhamster] Fix thumbnail extraction (#14780)
+ [xhamster] Add support for mobile URLs (#14780)
* [generic] Don't pass video id as mpd id while extracting DASH (#14902)
* [ard] Skip invalid stream URLs (#14906)
* [porncom] Fix metadata extraction (#14911)
* [pluralsight] Detect agreement request (#14913)
* [toutv] Fix login (#14614)

2017.12.02
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Core
+ [downloader/fragment] Commit part file after each fragment
+ [extractor/common] Add durations for DASH fragments with bare SegmentURLs
+ [extractor/common] Add support for DASH manifests with SegmentLists with
  bare SegmentURLs (#14844)
+ [utils] Add hvc1 codec code to parse_codecs

Extractors
* [xhamster] Fix extraction (#14884)
* [youku] Update ccode (#14872)
* [mnet] Fix format extraction (#14883)
+ [xiami] Add Referer header to API request
* [mtv] Correct scc extention in extracted subtitles (#13730)
* [vvvvid] Fix extraction for kenc videos (#13406)
+ [br] Add support for BR Mediathek videos (#14560, #14788)
+ [daisuki] Add support for motto.daisuki.com (#14681)
* [odnoklassniki] Fix API metadata request (#14862)
* [itv] Fix HLS formats extraction
+ [pbs] Add another media id regular expression