Issue #2972153 by dimitriskr, alexpott, smustgrave, andypost, kostyashupenko: Deprecate ThemeHandlerInterface::getBaseThemes and remove usages from core

Issue #2942001 by dimitriskr, alexpott, gaurav.kapoor, smustgrave, andypost, almaudoh: Deprecate ThemeHandlerInterface::rebuildThemeData() and use extension.list.theme service instead

Issue #2851394 by GoZ, hgunicamp, oknate, jungle, wolffereast, tameeshb, mmatsoo, ridhimaabrol24, jofitz, swarad07, tanc, shaktik, dimaro, shashikant_chauhan, MerryHamster, quietone, nitesh624, martin_q, boaloysius, gaurav.kapoor, nitvirus, ankithashetty, Munavijayalakshmi, kostyashupenko, leolando.tan, amit.drupal, ravi.shankar, akashkrishnan01, Swapnil_Kotwal, Saviktor, mrinalini9, anmolgoyal74, Venkatesh Rajan.J, shimpy, lomasr, Dinesh18, shubham.prakash, mahtab_alam, markdorison, cilefen, longwave, bleen, xjm, alexpott, gmaltoni: Fix grammar 'a' to 'an' when necessary

Issue #2776031 by fgm, andypost, voleger, yogeshmpawar, Berdir, joachim: Properly deprecate ThemeHandlerInterface install() and uninstall() also replace usage

Issue #2659940 by almaudoh, alexpott, phenaproxima, Jo Fitzgerald, markcarver, oriol_e9g, dawehner, dsnopek, jibran, larowlan: Extension System, Part III: ThemeExtensionList and ThemeEngineExtensionList

Issue #2872611 by alexpott: Optimise \Drupal\Core\Extension\ThemeHandler::refreshInfo() for the early installer

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2594937 by Peacog, cilefen, Sagar Ramgade, chgasparoto, aerozeppelin, iStryker, feraline, alvar0hurtad0, Cottser, Wim Leers, xjm, sebas5384, almaudoh, gvso, racarvalho1987: Empty 'libraries:' in theme .info.yml file produces confusing PHP warning

Issue #2719695 by alexpott, Mile23: Fix 'Drupal.Classes.ClassDeclaration.CloseBraceAfterBody' coding standard

Issue #2716685 by Mile23: Part 2: Fix several errors in the 'Drupal.Commenting.DocComment' coding standard

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2620176 by joelpittet, markcarver, hatuhay: Logo image settings form is broken, breaks per-theme overrides and can result in data loss

Issue #2574975 by alexpott, Cottser, izus: Allow (base-)themes to be excluded from the UI (e.g. blocks, Appearance)

Issue #2575421 by Cottser, mdrummond, lauriii, davidhernandez, LewisNyman, catch, alexpott, joelpittet, webchick, Bojhan, emma.maria, mortendk: Add a Stable base theme to core and make it the default if a base theme is not specified

Issue #2545972 by alexpott, joelpittet, ericjenkins, stefan.r, Wim Leers, Cottser: Remove all code usages SafeMarkup::checkPlain() and rely more on Twig autoescaping

Issue #2005546 by mdrummond, joelpittet, Manuel Garcia, lauriii, lokapujya, epari.siva, hosef, rpayanm, emma.maria, HOG, zetagraph, wmortada, rteijeiro, Cottser, hussainweb, madhavvyas: Use branding block in place of page template branding variables (site name, slogan, site logo)

Issue #2498691 by cilefen, mesch, deepakaryan1988, RavindraSingh, honzakuchar, darol100, kattekrab, Cottser, David_Rothstein: "Install and set as default" link on the Appearance page doesn't work

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

Issue #2470807 by LewisNyman, Dom., davidhernandez, emma.maria, lauriii, jp.stacey: Rename the default "Messages" region for all themes to "Highlighted"

Issue #2465887 by dawehner, amateescu, tim.plunkett: Extract the install/uninstall functionality to a ThemeInstaller

Revert "Issue #2470807 by LewisNyman, Dom., davidhernandez, emma.maria, jp.stacey, lauriii: Rename the default "Messages" region for all themes to "Highlighted""

This reverts commit 249e520b.

Issue #2470807 by LewisNyman, Dom., davidhernandez, emma.maria, jp.stacey, lauriii: Rename the default "Messages" region for all themes to "Highlighted"

Issue #1081266 by stefan.r, mikeytown2, jeroen.b, tsphethean, mfb, joseph.olstad, marcelovani: Avoid re-scanning module directory when a filename or a module is missing

Issue #2432791 by alexpott, vijaycs85, tim.plunkett, joshtaylor, Fabianx, Berdir, yched, bojanz: Skip Config::save schema validation of config data for trusted data.

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2090115 by alexpott, xjm: Don't install a module when its default configuration has unmet dependencies

Issue #356399 by dawehner, beejeebus, catch, sidharrell, klausi, nlisgo, Josh Waihi, Berdir, martin107: Optimize the route rebuilding process to rebuild on write

Issue #2289917 by Wim Leers, mdrummond, lauriii, Manuel Garcia, emma.maria, Scionar, davidhernandez: Convert "messages" page element into blocks

Issue #2306407 by lauriii, penyaskito, mortendk, pakmanlh, Wim Leers, ypogue: Remove breadcrumb from page template

Issue #2140511 by alexpott, Gábor Hojtsy, swentel, babruix, ohthehugemanatee, jessebeach, Berdir: Configuration file name collisions silently ignored for default configuration

Issue #2392319 by alexpott, effulgentsia: Config objects (but not config entities) should by default be immutable

git commit -m 'Issue #2377397 by Wim Leers, alexpott: Themes should use libraries, not individual stylesheets'

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

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.