.netrc file: add support for passwords containing spaces

[alindt]

• I've verified and I assure that I'm running youtube-dl 2017.06.18

$  youtube-dl --version
2017.06.18

• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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Description of your issue, suggested solution and other information

$ cat .netrc
machine facebook login "user_login" password "password with spaces"

$ cat .config/youtube-dl/config 
--netrc

$ youtube-dl https://www.facebook.com/XXXXXXX/videos/XXXXXXX/
WARNING: parsing .netrc: bad follower token '?????' (/home/user/.netrc, line 1)

Is should be possible to quote passwords containing spaces.

[yan12125]

.netrc is parsed by Python instead of youtube-dl. There's a patch at python/cpython#127 fixing this but seems it's stalled.

[xenithorb]

I'm also affected by this.

For posterity, #14177 was a dupe I found before this issue, and wasn't properly linked.