Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2569069 by stefan.r, mr.baileys, alexpott, lauriii: Replace TranslationWrapper with TranslatableString and deprecate TranslationWrapper

Issue #2457551 by Gábor Hojtsy, rteijeiro, keopx, eiriksm, alexpott: Regression: optional default configuration is not translatable anymore in locale

Issue #2460259 by sasanikolic, ameenkhan07: Multiple calls to LocaleConfigManager::getStringTranslation can return multiple new translation objects for the same source

Issue #2459971 by Gábor Hojtsy: The langcode key on configuration files is not explicit in configuration schema

Issue #2212069 by Gábor Hojtsy, pjonckiere, rteijeiro, cilefen: Non-English Drupal sites get default configuration in English, edited in English, originals not actually used if translated

Issue #2225427 by ianthomas_uk, martin107, JeroenT, LoMo: Remove remaining uses of deprecated language functions (mostly in object oriented code)

Issue #2144413 by tstoeckler, YesCT, robertdbailey, webflo, Schnitzel, Wim Leers, kfritsche, Jose Reyero, Gábor Hojtsy, prodosh: Config translation does not support text elements with a format

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().

Issue #1533250 by YesCT, fran seva, TravisCarden, xjm, sriharsha.uppuluri | NROTC_Webmaster: Many coding standards clean-ups in locale module.

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

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

Issue #2224887 by alexpott, Berdir, Gábor Hojtsy, Jalandhar: Language configuration overrides should have their own storage.

Issue #2219499 by Berdir, alexpott, Gábor Hojtsy, vijaycs85, swentel: Generalize language config override responsibility.

Issue #2098119 by beejeebus, alexpott, chx: Replace config context system with baked-in locale support and single-event based overrides.

Issue #2162013 by alexpott, Berdir, sun, pwolanin: Critical performance regression due to config schema + TypedData lookups in installer.

Issue #2057019 by janstoeckler: Remove Unused local variable $string from /core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php.

Issue #1813762 by ParisLiakos, Jose Reyero, YesCT, japicoder, attiks: Introduce unified interfaces, use dependency injection for interface translation.

Issue #1905152 by Gábor Hojtsy, Jose Reyero, vijaycs85, YesCT, penyaskito: Integrate config schema with locale, so shipped configuration is translated.