[generic] Support data-video-url for YouTube embeds (Fixes #2862)
Add a duplicate check to /extractor/common.py playlist_result function
Add a _TEST_
Move duplicate check to generic.py
if there is more than one subtitle for the language, use the first one
Add Patreon extractor
Add import for Patreon extractor
fix exception
[jove] Add new extractor. Closes #3177
[fm4] Add new extractor
Fix CSS parsing for Patreon

Some of the CSS classes end in " double", so this commit refines the
HTML parsing to account for both kinds of classes, and also adds an
additional test case.
Add more information about running tests, add syntax highlighting

There was no information in the README about how to handle multiple
tests for a given extractor. This commit adds an explanation of how this
is handled.

It also adds some syntax highlighting.
[arte] Do not filter formats when there are no videos of requested lang code (Closes #3433)
Merge pull request #3431 from sehaas/fm4

[fm4] Add new extractor
[fm4] Remove unused imports and minor changes
[orf] Move all ORF extractors in one place
Credit @sehaas for ORF FM4 extractor (#3431)
[downloader/common] Fix typo
[reverbnation] Make sure that the thumbnail url contain the protocol

They are protocol relative.
[reverbnation] Modernize test