Issue #2528178 by dawehner, amateescu, larowlan, tim.plunkett, jibran, catch, jhodgdon, effulgentsia, Berdir: Provide an upgrade path for blocks context IDs #2354889 (context manager)

Issue #2351015 by plach, effulgentsia, Wim Leers, dawehner, martin107, damiankloip, cilefen, Fabianx, catch, pwolanin, Damien Tournoud, znerol, YesCT, larowlan: URL generation does not bubble cache contexts

Issue #2502785 by dawehner, effulgentsia, tim.plunkett, amateescu, Fabianx, Wim Leers, catch, dsnopek, EclipseGc, yched, Berdir, larowlan, mondrake, olli: Remove support for $form_state->setCached() for GET requests

Issue #2490420 by amateescu, larowlan, Berdir, dpi: EntityAutocomplete element settings allows sql injection and for arbitrary user-supplied data to be passed into unserialize()

Issue #2461087 by Wim Leers, dawehner: Add 'no_cache' route option to mark a route's responses as uncacheable (was: Cron run response should not be cacheable)

Issue #2418017 by Wim Leers, YesCT, dawehner, webchick, jibran, amateescu, hussainweb: Implement autocomplete UI for the link widget

Issue #1959806 by amateescu, jibran, goldorak, Wim Leers, yched, dawehner: Provide a generic 'entity_autocomplete' Form API element

Issue #2362517 by Wim Leers: Improve default 403/404 exception HTML subscriber: don't duplicate the page render pipeline, use the routing system — add system.403 and system.404 routes.

Issue #2340251 by iMiksu, alexpott, tim.plunkett, dawehner, Wim Leers: Remove most remaining url() calls.

Issue #2316203 by olli, tim.plunkett | Charles Belov: Fixed Permission "Use the administration pages and help" grants permission to configure Image Toolkit.

Issue #2301317 by pwolanin, dawehner, Wim Leers, effulgentsia, YesCT, xjm, alexpott: MenuLinkNG part4: Conversion.

Revert "Issue #2301317 by pwolanin, effulgentsia, Wim Leers, dawehner, alexpott: MenuLinkNG part4: Conversion."

This reverts commit fd2db9cd.

Issue #2301317 by pwolanin, effulgentsia, Wim Leers, dawehner, alexpott: MenuLinkNG part4: Conversion.

Issue #1987848 by disasm, ocsilalala, kim.pepper, pwieck, Cottser, pratik60, h3rj4n, pfrenssen, InternetDevels, ParisLiakos, rgoodine, tlyngej, vijaycs85, robeano: Convert system_theme_default() to a new style controller.

Issue #2026431 by YesCT, dawehner, Crell: Make ContentNegotiation a 'internal' service, used only by the router, so that core or contrib can implement real negotiation.

Issue #1316692 by tim.plunkett, dawehner: Convert hook_admin_paths() into declarative properties on routes.

Issue #2047633 by pwolanin, dawehner, kim.pepper, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit.

Revert "Issue #2047633 by dawehner, pwolanin, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit."

This reverts commit 531fd593.

Issue #2047633 by dawehner, pwolanin, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit.

Issue #2068471 by dawehner, Crell, tim.plunkett, jibran, fubhy, larowlan: Normalize Controller/View-listener behavior with a Page object.