Issue #2045927 by herom, martin107, ianthomas_uk, Xano, michaellander, Sutharsan: Replace all drupal_alter() deprecated function calls.

Issue #1996238 by sun, nod_, damiankloip, Wim Leers, longwave, alexpott, Xano, mdrummond, Mark Carver, Jeff Burnz, highrockmedia, joelpittet, et al: Replace hook_library_info() by *.libraries.yml file.

Issue #2173655 by Cottser, xjm, jessebeach, alexpott, rlmumford: Refactor theme() to _theme(); make it a private API to discourage module developers from circumventing the renderable build system.

Issue #2093161 by rbayliss, haithem_pro, sandipmkhairnar, InternetDevels, longwave, idflood, Sumeet.Pareek, sidharthap, xeniak, ianthomas_uk: Remove all calls to drupal_json_encode() in favour of \Drupal\Component\Utility\Json::encode().

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

Issue #1954892 by dawehner, David_Rothstein, tim.plunkett: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system.

Issue #1998638 by damiankloip, dawehner, kim.pepper, cosmicdreams, alexpott, larowlan, Damien Tournoud: Replace almost all remaining superglobals (, , etc.) with Symfony Request object.

Issue #1998638 by damiankloip, dawehner, kim.pepper, cosmicdreams, larowlan, Damien Tournoud: Replace all remaining superglobals (, , etc.) with Symfony Request object.

Revert "Issue #1954892 by dawehner, tim.plunkett, David_Rothstein, effulgentsia: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system."

This reverts commit fc04601c.

Issue #1954892 by dawehner, tim.plunkett, David_Rothstein, effulgentsia: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system.

Issue #2049207 by dlu, blakehall, janstoeckler, ramlev, Moderate | Cottser: Replace .tpl.php with .html.twig in documentation.

Issue #1793648 by nod_, kmox83, droplet, rteijeiro: Follow-up: replace all occurence of Drupal.settings with drupalSettings.

Issue #1987602 by glennpratt, juampy, pwieck, vijaycs85, dawehner, tim.plunkett, effulgentsia: Convert ajax_form_callback() to a new style controller.

This reverts commit 127b54a6.

Issue #2019481 by nod_: JavaScript AJAX commands object is borked: it is shared among all Drupal.ajax instances, preventing scoped overrides.

Issue #1944472 by larowlan, quicksketch, effulgentsia: Add generic content handler for returning dialogs.

Issue #1870764 by quicksketch, dawehner, frega, larowlan, nod_: Add an ajax command which makes it easy to use the dialog API in complex cases.

Issue #1829224 by alexpott, pfrenssen, vijaycs85, lirantal: Convert the 'theme_default()' variable to CMI.

Issue #1875632 follow-up by nod_, Wim Leers, effulgentsia: Added wrapper function for JS settings merging behavior, fix tabledrag.

Issue #1356170 by ohnobinki, tim.plunkett: Remove all uses of array_merge_recursive(), or document why they are being used instead of NestedArray::mergeDeep().

Issue #1667742 by larowlan, nod_, effulgentsia, jessebeach, sun: Change notice: Add abstracted dialog to core (resolves accessibility bug).

Issue #1238484 by mrfelton, ry5n, aspilicious, Bojhan, Xano, nod_, rootatwc, effulgentsia, chx, sun: Ability to mark the form buttons to be of a specific type (so that they can be styled differently).

Issue #1802072 by fubhy, Stalski: Ajax callbacks should be callbacks defined as function or class method.

Issue #1496458 by swentel, pcambra, n3or, kbasarab, sun, marcingy: Convert maintenance mode settings to configuration system.

- Patch #1677304 by socketwench, Niklas Fiekas: Remove drupal_deliver_page(), ajax_deliver(), drupal_deliver_html_page().

Issue #1071818 by JeremyFrench, nod_, reglogge, anthbel, xjm, sun, NROTC_Webmaster, lliss, Cottser: Fixed Lazy-loading CSS fails in IE.