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 #1979468 by Wim Leers, nod_, pwolanin, longwave, thedavidmeister, jessebeach, larowlan | catch: .active from linkGenerator(), l() and theme_links() forces an upper limit of per-page caching for all content containing links.

Somehow this broke PHPUnit, so rolling back for now.

This reverts commit 91b465bd.

Issue #1862202 by plach, Berdir, katbailey, ParisLiakos, alexpott, chx, sun, larowlan, Gábor Hojtsy, cosmicdreams, vijaycs85, YesCT, penyaskito, andypost, Albert Volkman, joelpitett: Objectify the language system.

Issue #1649780 by effulgentsia, jibran, Wim Leers, nod_, hefox, joelpittet, kaare, BarisW, sun, rbayliss, Cottser, fubhy: Remove first/last/odd/even classes in favor of CSS3 pseudo selectors.

Issue #2164597 by longwave, StephaneQ, emok: Doxygen @return tag missing for drupal_render_children.

Issue #2155701 by sun: Installer starts with fatal error/exception 'table 'semaphore' not found' if settings.php contains  already.

Issue #2171015 by alexpott: Drupal 8 HEAD broken: installing Language module fails, after that cannot install any other module.

Issue #2166065 by alexpott, mtift: Replace config_install_default_config with ConfigInstaller service.

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

Issue #2042807 by tim.plunkett, pwolanin, ianthomas_uk, jhodgdon: Convert search plugins to use a ConfigEntity and a PluginBag.

Issue #2168113 by penyaskito, jessebeach, catch: Add leading underscore and other discouragement to drupal_add_css() and drupal_add_js().

Revert "Issue #1979468 by Wim Leers, pwolanin, nod_, thedavidmeister, larowlan: .active from linkGenerator(), l() and theme_links() forces an upper limit of per-page caching for all content containing links."

This reverts commit 624296e7.

Issue #1979468 by Wim Leers, pwolanin, nod_, thedavidmeister, larowlan: .active from linkGenerator(), l() and theme_links() forces an upper limit of per-page caching for all content containing links.

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

Issue #2160581 by vijaycs85, Wim Leers: Remove drupal_add_js() + drupal_add_library() from install.core.inc.

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

Issue #2005716 by tim.plunkett, msonnabaum, dawehner, alexpott, effulgentsia: Promote EntityType to a domain object.

Issue #111702 by mvc, penyaskito, naxoc, jenlampton, montesq: Set fixed "from:" and add "Reply-to:" to improve deliverability of Drupal mail.

Issue #2002708 by rahul.shinde, somepal, kerasai, arknoll: Remove unused local variables from core/includes/common.inc.

Issue #2001206 by andypost, penyaskito, herom, Crell, ebeyrent, DmitryDrozdik: Replace drupal_container() with Drupal::service().