Issue #1957330 by ParisLiakos, twistor: Make possible for parsers and fetchers to expose configuration through plugins.

Issue #1847002 by tim.plunkett, effulgentsia, msonnabaum: Move entity type classes from Drupal$provider\Plugin\Core\Entity to Drupal$provider\Entity.

Issue #1906692 by Simon Georges, jmarkel: String cleanup: make strings consistent in DefaultFetcher::fetch.

Issue #1937600 by Berdir, rootatwc | webchick: Determine what services to register in the new Drupal class.

Issue #1849752 by effulgentsia, Berdir, jibran, neclimdul: Abstract non-Drupal-specific parts of AnnotatedClassDiscovery into a Drupal\Component base class.

Issue #293318 by alex_b, Berdir, rootatwc, Aron Novak, mustafau, akahn: Convert Aggregator feeds into entities.

Issue #1447736 by rbayliss, mikeytown2, effulgentsia, kim.pepper, Fabianx, boombatower: Adopt Guzzle library to replace drupal_http_request().

- Patch #1683644 by chx, EclipseGc, tim.plunkett, aspilicious, xjm, dawehner, effulgentsia: use Annotations for plugin discovery.

- Patch #1497366 by neclimdul, effulgentsia, EclipseGc, merlinofchaos: introduce Plugin System to core.