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

Issue #2118703 by Wim Leers, amateescu: Introduce #post_render_cache callback to allow for personalization without breaking the render cache.

Issue #2057259 by alexpott, cweagans, swentel: Fixed Malformed modulename.info.yml file causes fatal error.

Issue #2102125 by dawehner, tim.plunkett, neclimdul, pwolanin, YesCT, damiankloip, Tim Bozeman: Big Local Task Conversion.

Issue #1851414 by nod_, quicksketch, frega, dawehner, damiankloip: Convert Views to use the abstracted dialog modal.

Issue #2045931 by PerthSam152, LinL, adsw12, joelpittet: Replace all module_exists() deprecated function calls.

This reverts commit cc84f390 - bad
commit message.

Issue #2014017 by jlbellido, alvar0hurtad0, undertext, benjy, penyaskito, LinL: Replace drupal_container() with Drupal::service() in the system module.

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

Issue #1798732 by sun, Dean Reilly, mbrett5062, chx, westie, alexpott, juanolalla, Mark Carver, catch, jthorson, cam8001, Berdir: Convert install_task(), install_time() and install_current_batch() to use the state system.

Issue #2100329 by cosmicdreams: Use \Drupal instead of Drupal to make IDEs and static code analyse tools happy.

Issue #2095249 by mcjim: Change description text for admin/config/system/site-information to remove 'number of posts per page'.

Issue #1751194 by Cottser, mikl, effulgentsia, benjifisher: Introduce hook_theme_suggestions_HOOK() and hook_theme_suggestions_HOOK_alter().

Issue #1839318 by JohnAlbin, echoz: Added Replace drupal.base.css library with normalize.css for all themes.

Issue #2009674 by pplantinga, Samvel, dmitrii: Replace theme() with drupal_render() in system module.

Issue #1199946 by alexpott, fubhy, bojanz, steinmb, chx, catch: Fixed Disabled modules are broken beyond repair so the 'disable' functionality needs to be removed.

Issue #2089635 by tim.plunkett, disasm, larowlan: Convert non-test non-form page callbacks to routes and controllers.

Issue #2085907 by YesCT, Gábor Hojtsy: Ensure all configuration entities have an Edit/Configure tab by default.

Issue #1834002 by Gábor Hojtsy: Fixed Delete operations are all over the place. Remove tabs, provide title in routing.

Issue #1981368 by tim.plunkett, Crell, webchick: Convert all routes to 'module_name().foo_bar()' naming convention.

Issue #1987816 by pdrake, disasm, ParisLiakos, pguillard, vijaycs85, dawehner: Convert system_batch_page() to a new style controller.

Issue #1987814 by juampy, tim.plunkett, lliss, kushrohra: Convert system_admin_menu_block_page() to a new style controller.

Issue #1987818 by jlbellido, MattDanger, disasm, vijaycs85: Convert system_date_format_language_overview_page() to a new style controller.

Issue #1987810 by nick_schuch, dawehner, vijaycs85, tim.plunkett: Convert system_admin_config_page() to a new style controller.

Issue #1987808 by h3rj4n, vijaycs85, Dave.Ingram, tim.plunkett: Convert system_admin_compact_page() to a new style controller.