[cnn] Add support for articles with videos (fixes #4541)
[arte.tv:+7] Make quality optional (Closes #4583)
[arte.tv] Fix typo
[archiveorg] most metadata fields are optional

Example: https://archive.org/details/Cops1922
Merge pull request #4590 from derrotebaron/master

[archiveorg] most metadata fields are optional
[archiveorg] Add test, simplify and modernize
[bbccouk] Switch to new JSON playlist format (Closes #4588)
Merge pull request #4543 from akretz/cnn_fix

[cnn] Add support for articles with videos (fixes #4541)
[cnn] Improve regexes and fix test