Issue #2300817 by joshi.rohit100, er.pushpinderrana, tim.plunkett, ianthomas_uk, LinL, dawehner: Remove path_is_admin() as it is deprecated

Issue #2362227 by dawehner, mpdonadio, znerol, tim.plunkett, skipyT: Replace all instances of current_path()

Issue #2378263 by Wim Leers: hook_library_alter() must be manually invoked by users of LibraryDiscovery, and has no test coverage

Issue #2346937 by dawehner, larowlan, Wim Leers, claudiu.cristea, msonnabaum: Implement a Renderer service; reduces drupal_render / _theme service container calls

Issue #1938918 by joelpittet, lauriii, botanic_spark, mdrummond, nielsonm: Convert menu theme tables to table #type.

Issue #2324371 by lauriii, aneek, chx, joelpittet, webflo, Fabianx, rteijeiro: Fix common HTML escaped render #key values due to Twig autoescape.

Issue #2183075 by valderama, dinarcon, er.pushpinderrana, amitgoyal, umar-ahmad: Tidy up css.gzip and js.gzip configuration.

Issue #2361681 by Wim Leers: drupal_render(): invert second argument ($is_recursive_call -> $is_root_call) => more strict, better DX/TX.

Issue #2362123 by Wim Leers: Drupal_page_header() and drupal_send_headers() are dead code: already deprecated, zero uses remain: remove.

Issue #2350949 by Wim Leers: Add hook_page_attachments(_alter)() and deprecate hook_page_build/alter().

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().

Issue #2350877 by dawehner, Wim Leers, hussainweb: Deprecate/rename drupal_add_feed(), drupal_add_html_head(), drupal_add_html_head_link(), drupal_add_http_header(), and allow to be set declaratively in #attached.

Issue #2184907 by JeroenT, ParisLiakos, ianthomas_uk, hussainweb, dawehner: Remove uses of drupal_add_http_header and related functions.

Issue #2347831 by xjm, effulgentsia: Fix documentation for \Drupal::url(), \Drupal::l(), etc. (and fix the change record).

Issue #2343661 by larowlan, tim.plunkett | xjm: Rename l() to _l() and url() to _url(), and document replacements.

Issue #1869476 by rteijeiro, LewisNyman, lauriii, Wim Leers, mdrummond, swentel, hosef, cbiggins, larowlan, sun, EclipseGc, Gábor Hojtsy: Convert global menus (primary links, secondary links) into blocks.

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

Issue #2340123 by Wim Leers: Setting cache tags can be tricky: use strings instead of nested arrays to improve DX.

Issue #2325571 by asif_khan, omers | dawehner: Replace _theme() calls by calls to \Drupal::theme()->render().

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

Issue #2329795 by fietserwin, bzitzow, alexrayu, tstoeckler | illutek, dawehner: Fixed Make it possible to add information to theme info files during development.

Issue #2273277 by Wim Leers, effulgentsia, Fabianx: Fixed Figure out a solution for the problematic interaction between the render system and the theme system when using #pre_render.

Issue #2121713 by tim.plunkett, dawehner, rteijeiro, jiv_e: Move drupal_html_id() and drupal_html_class() to Drupal\Component\Utility.