Issue #2300829 by Jose Reyero: Fixed Clean up LocaleConfigManager / TypedConfigManager features and cache duplications.

Issue #697760 by sun: Replace getInfo() in tests with native phpDoc + annotations (following PHPUnit).

Issue #2246665 by jaredsmith, martin107, YesCT, filijonka, tstoeckler: Typehint with Drupal\Core\Language\LanguageInterface instead Drupal\Core\Language\Language.

Issue #2271967 by Jose Reyero, alexpott, amitgoyal: Fixed and use TypedConfigManagerInterface/TypedConfigManager.

Issue #2158571 by tstoeckler, dawehner, kgoel, tim.plunkett, catch, effulgentsia: Routes added in RouteSubscribers cannot be altered.

Issue #1067408 by alexpott, Jalandhar, jessebeach, Désiré, neetu morwani, dawehner, sun: Themes do not have an installation status.

This reverts commit ae8be3cc.

Issue #2002134 by fago, yched, amateescu, effulgentsia: Move TypedData metadata introspection from data objects to definition objects.

Issue #1981858 by Berdir, tim.plunkett, longwave, Les Lim: Rename hook_entity_info/alter() to hook_entity_type_build/alter().

Issue #2167039 by likin, dawehner, Wim Leers, tstoeckler, vijaycs85: Regression: page cache tags broken, also: some routes incorrectly use _controller -> No page object in template variables -> Fatal in seven_preprocess_page().

Issue #1862202 by plach, Berdir, katbailey, ParisLiakos, alexpott, chx, sun, larowlan, Gábor Hojtsy, cosmicdreams, vijaycs85, YesCT, penyaskito, andypost, Albert Volkman, joelpitett: Objectify the language system.

Issue #2005716 by tim.plunkett, msonnabaum, dawehner, alexpott, effulgentsia: Promote EntityType to a domain object.

Issue #1952394 by vijaycs85, tstoeckler, webflo, Gábor Hojtsy, Schnitzel, falcon03, YesCT, kfritsche, Ryan Weal, dagmita, likin, toddtomlinson, nonsie, Kristen Pol, dawehner, tim.plunkett, penyaskito, EclipseGC, larowlan, robertdbailey, helenkim, David Hernández, EllaTheHarpy, lazysoundsystem, juanolalla, R.Hendel, Kartagis: Add configuration translation user interface module.