Log Message:
youtube-dl: Update to 20190218

Changes:
version 2019.02.18

Extractors
* [tvp:website] Fix and improve extraction
+ [tvp] Detect unavailable videos
* [tvp] Fix description extraction and make thumbnail optional
+ [linuxacademy] Add support for linuxacademy.com (#12207)
* [bilibili] Update keys (#19233)
* [udemy] Extend URL regular expressions (#14330, #15883)
* [udemy] Update User-Agent and detect captcha (#14713, #15839, #18126)
* [noovo] Fix extraction (#19230)
* [rai] Relax URL regular expression (#19232)
+ [vshare] Pass Referer to download request (#19205, #19221)
+ [openload] Add support for oload.live (#19222)
* [imgur] Use video id as title fallback (#18590)
+ [twitch] Add new source format detection approach (#19193)
* [tvplayhome] Fix video id extraction (#19190)
* [tvplayhome] Fix episode metadata extraction (#19190)
* [rutube:embed] Fix extraction (#19163)
+ [rutube:embed] Add support private videos (#19163)
+ [soundcloud] Extract more metadata
+ [trunews] Add support for trunews.com (#19153)
+ [linkedin:learning] Extract chapter_number and chapter_id (#19162)