apply ratelimit to f4m
[comcarcoff] add webpage_url datum
[5min] Remove helper method and modernize

Previously, other extractor would go call a private(!) helper method. Instead, just hardcode the 5min:video_id format - it's not if that would ever change.
[streamcz] Update extractor
Fix imports and general cleanup

· Import from compat what comes from compat. Yes, some names are available in utils too, but that's an implementation detail.
· Use _match_id consistently whenever possible
· Fix some outdated tests
· Use consistent valid URL (always match the whole protocol, no ^ at start required)
· Use modern test definitions
[keek] Modernize and extract uploader
[keek] remove unused import
[orf] Modernize
[test_unicode_literals] Import from test.helper
Merge pull request #3927 from qrtt1/master

apply ratelimit to f4m
[adultswim] Improve segment duration extraction
[bbccouk] Fix vpid warning
[bandcamp:album] Make path optional (Closes #4461)
[Restudy] Add new extractor for restudy.dk
[restudy] Simplify and extract all formats
Merge branch 'Mortal-restudy'
Credit @Mortal for restudy (#4463)
Merge branch 'master' of github.com:rg3/youtube-dl
Merge branch 'master' of github.com:rg3/youtube-dl
Merge remote-tracking branch 'fstirlitz/master'