Issue #2501705 by tetranz, pwolanin, Cottser, joelpittet, akalata: Remove SafeMarkup::set() in LinkGenerator and document SafeMarkup::set() in LinkGeneratorTest

Issue #2491155 by mikeburrelljr, Mac_Weber, opdavies: Update drupal.org and kernel.org URLs in core modules (Follow-up to 2489912)

Issue #2335661 by Wim Leers, pwolanin, dawehner, Fabianx, larowlan, catch, Berdir: Outbound path & route processors must specify cacheability metadata

Issue #2455083 by dawehner, larowlan, klausi, David_Rothstein, hefox, tsphethean, dstol, DamienMcKenna, Pere Orga, benjy: Open redirect fixes from SA-CORE-2015-001 need to be ported to Drupal 8

Issue #2364157 by mpdonadio, dawehner, martin107, Berdir, pcambra, naveenvalecha, tim.plunkett: Replace most existing _url calls with Url objects

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

Issue #2343759 by pwolanin, larowlan, dawehner, tim.plunkett, effulgentsia, xjm, Wim Leers: Provide an API function to replace url()/l() for external urls.