Log Message:
Updated youtube-dl to 20170723.

Core

    [YoutubeDL] Improve default format specification (#13704)
    [YoutubeDL] Do not override id, extractor and extractor_key for
    url_transparent entities
    [extractor/common] Fix playlist_from_matches

Extractors

    [itv] Fix production id extraction (#13671, #13703)
    [vidio] Make duration non fatal and fix typo
    [mtv] Skip missing video parts (#13690)
    [sportbox:embed] Fix extraction

    [npo] Add support for npo3.nl URLs (#13695)

    [dramafever] Remove video id from title (#13699)

    [egghead:lesson] Add support for lessons (#6635)

    [funnyordie] Extract more metadata (#13677)
    [youku:show] Fix playlist extraction (#13248)

    [dispeak] Recognize sevt subdomain (#13276)

    [adn] Improve error reporting (#13663)
    [crunchyroll] Relax series and season regex (#13659)

    [spiegel:article] Add support for nexx iframe embeds (#13029)
    [nexx:embed] Add support for iframe embeds

    [nexx] Improve JS embed extraction

    [pearvideo] Add support for pearvideo.com (#13031)