Issue #2246661 by ivanjaros: Some templates are missing 'Default theme implementation ..' statement.

Issue #2256679 by alexpott, tim.plunkett: Fixed Use config schema to determine which config entity properties to export regardless of whether they are public or protected.

Issue #2247779 by Wim Leers, larowlan, dawehner: Allow #pre_render, #post_render and #post_render_cache callbacks to be service methods.

Issue #2275877 by Mixologic, duellj, Les Lim, Xano, David Strauss: Replace master/slave terminology with primary/replica.

Issue #1914914 by purdy_nc, meba, chx, heyrocker: Add to docs of file_scan_directory to discuss excluding config

Issue #2281419 by t0xicCode, joshi.rohit100, SiliconMind: Fix up docs for FieldItemInterface methods

Issue #2260043 by t0xicCode, amitgoyal: Remove lingering references to obsolete field crud and attach topics and functions

Issue #2243439 by amitgoyal, jonreid, mark.labrecque, mpv, pwolanin, scor, cilefen, sun: Fix up docs about config file/database locations in settings.php and READMEs in directories

Issue #2267159 by juampy, xjm, alexpott: Remove nonexistent parameter from WebTestBase::assertNoLink docs

Issue #1912610 by amitgoyal, BryanCGreen24, lokapujya, Rajendar Reddy, echoz, barraponto, LewisNyman, pixelwhip: Rename layout classes to follow the layout style naming convention.

Issue #2228763 by larowlan, alexpott, martin107, jessebeach, xjm: Create a comment-type config entity and use that as comment bundles, require selection in field settings form.

Issue #1939092 by mgifford, dbazuin, jenlampton, azinoman, pwieck, Cottser, joelpittet, larowlan: Convert theme_mark() to Twig.

Issue #1898070 by benjifisher, jjcarrion, LinL, idflood, joelpittet, oshelach, tlattimore, Les Lim, sergey.semashko, jesse.d, bdgreen, jenlampton, Cottser, duellj, artofeclipse, vlad.dancer, steveoliver, EVIIILJ, c4rl, elv, OpenChimp: File.module - Convert theme_ functions to Twig.

Issue #2151821 by joelpittet, JacobSanford, jjcarrion, rteijeiro, c4rl, IshaDakota, pplantinga, gnuget, longwave, jeanfei, sbudker1: Convert theme_system_config_form() to Twig

Issue #1898420 by mondrake, joelpittet, InternetDevels, claudiu.cristea, c4rl, DamienMcKenna, Albert Volkman, shanethehat, thedavidmeister: Image.module - Convert theme_ functions to Twig.

Issue #2250325 by jhodgdon, azinck, splatio: Fixed Route book.render (path /book) does not seem to work.

Issue #2052473 by ricky.middaugh, lokapujya, Jalandhar, mgifford, jessebeach, BarisW, falcon03: Add aria-label or aria-describedby attributes to all <nav> elements.

Issue #2080343 by connork, izus, rahul.shinde, lokapujya | mrsinguyen: Remove Unused local variables from system module.

Issue #2089331 by grom358 | thedavidmeister: [meta] Replace calls to check_plain() with Drupal\Component\Utility\String::checkPlain().

Issue #2264753 by cfox612, Cottser, a-fro, joelpittet: Convert theme_update_last_check to update-last-check.html.twig.

Issue #2152215 by joelpittet, mr.baileys, benjifisher, martin107, rteijeiro, hussainweb, shanethehat, jenlampton, kpa, AnythonyR, EVIIILJ, kgoel, Cottser, dsdeiz, hanpersand, bayousoft: Convert theme_form_element_label() to Twig

Issue #2282477 by tim.plunkett: Fixed ViewListBuilder::getDisplaysList() does not handle empty admin strings.

Issue #2229163 by Michael Hodge Jr, rixter, thechanceg, bburg | Berdir: Remove node_type->has_title.

Issue #2283929 by tim.plunkett: Clean up condition plugins to have schema support and to allow them to be optional.

Issue #2283969 by tim.plunkett: Add a protected BlockBase::blockAccess() to contain plugin-specific logic.

Revert "Issue #2125621 by anandps, mgifford, davidhernandez, jessebeach, mparker17: Fixed drupala11y.org finds two new color contrast issues."

Needs more discussion/review, given strong visual impact.

This reverts commit cdf25d79.