Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2448357 by amateescu: Config entity forms need to have access to an updated entity object at all times

Issue #2388349 by almaudoh: FormState::cleanValues() doesn't conform with the FormStateInterface documentation

Issue #2407361 by cilefen, JeroenT, hussainweb, neclimdul, ircmaxell, tim.plunkett, nlisgo, Crell: Move usages of drupal_html_id() to Html::getUniqueId()

Revert "Issue #2407361 by JeroenT, cilefen, hussainweb: Move usages of drupal_html_id() to Html::getUniqueId()"

This reverts commit 85b8c837.

Issue #2407361 by JeroenT, cilefen, hussainweb: Move usages of drupal_html_id() to Html::getUniqueId()

Issue #2426181 by effulgentsia, mpdonadio, xjm: Add a Url::fromUserInput() wrapper method for generating URLs from user-entered paths

Issue #2417647 by Wim Leers, effulgentsia: Add leading slash to paths within 'user-path:' URIs, to allow 'user-path:' URIs to point to the <none> route

Issue #2417333 by Wim Leers, pwolanin, xjm, dawehner: Add support for user-path: scheme to Url class

Issue #2392319 by alexpott, effulgentsia: Config objects (but not config entities) should by default be immutable

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

Issue #2367743 by rpayanm, Miroling, YesCT, ianthomas_uk, shadik, gaurav.pahuja: Remove usages of drupal_form_submit() and update documentation

Issue #2113243 by rpayanm, Xano, tstoeckler: Rename BaseFormIdInterface::getBaseFormID() to BaseFormIdInterface::getBaseFormId()

Issue #1985406 by jhedstrom, alexpott, Dave Reid, olli: #states not supported for elements in formatter settings being displayed on Views field handler form

Issue #2226863 by cs_shadow, filijonka, joelpittet, pguillard: Update stale references to theme functions that have been converted to Twig

Issue #2328111 by dawehner, martin107, neclimdul: Replace most instances of the DRUPAL_ROOT constant with the app.root container parameter.

Issue #2368975 by damiankloip: Fixed ElementInfoManager::buildInfo() processes info data on every request.

Issue #2355179 by legolasbo, er.pushpinderrana: Remove usage of form_get_cache() and form_set_cache().

Issue #2242749 by znerol, torotil, rszrama, larowlan, dawehner, penyaskito, tim.plunkett, sun, Damien Tournoud, David_Rothstein,  effulgentsia: Fixed Port Form API security fix SA-CORE-2014-002 to Drupal 8.

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2337709 by tim.plunkett: Convert form_state_values_clean() to FormStateInterface::cleanValues().

Issue #2335659 by tim.plunkett, dawehner, effulgentsia, sun: Remove FormState ArrayAccess usage from core.

Issue #2336405 by tim.plunkett: Fixed Follow-up: FormStateInterface::getGroups() should return by reference.

Issue #2334405 by almaudoh, drunken monkey: Clean up documentation links to functions moved to render element classes