youtube-dl 2019.03.01

Core

• [downloader/external] Add support for rate limit and retries for wget

• [downloader/external] Fix infinite retries for curl (#19303)

Extractors

• [npo] Fix extraction (#20084)
• [francetv:site] Extend video id regex (#20029, #20071)

• [periscope] Extract width and height (#20015)

• [servus] Fix extraction (#19297)
• [bbccouk] Make subtitles non fatal (#19651)
• [metacafe] Fix family filter bypass (#19287)