Begin migration to an event based model.
Move pubsubhubbub to an event listener.
Update ProcessorInterface.
Update FeedInterface.
Make SyndicationParser batch.
Update Crypto usage.
Covert ParserResult to an SplDoublyLinkedList and feed items to classed objects.
Move plugin listener registration to a separate event subscriber.
More detailed batch messages.
Remove getSourceElement.
Remove old useless tests.
Ensure State::progress() always returns a float.
Refactor FetcherResult.
Cleanup tests.
Remove useless user settings.
Add ParserResultTest
Add tests for RawFetcherResult.
Rewrite CSV parser and add unit tests.
Unit tests for sitemap parser. Make it batch.
Add tests for syndication parser.