Issue #2571655 by jan.stoeckler, maxocub, tstoeckler: ConfigNamesMapper::hasTranslatable has flawed logic

Issue #2295255 by dawehner, tstoeckler, k4v, kgoel: Convert ConfigMapperInterface::populateFromRequest() to use RouteMatch

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 #2281619 by dawehner, tim.plunkett: Convert most direct usages within module code of routing related request attributes to use RouteMatchInterface instead

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

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

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.