Issue #2388247 by pguillard, snehi, joelpittet, sriharsha.uppuluri: Documentation refers to _theme() function, which has been removed

Issue #2122087 by rakesh.gectcr, snehi, InternetDevels, Xano, alvar0hurtad0: Remove references to hook_init()

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2574717 by dawehner, hussainweb, lauriii, pwolanin, davidhernandez, xjm, stefan.r, webchick, Wim Leers: Remove PHPTemplate, and add test coverage for multiple theme engine support

Issue #2549393 by alexpott, dawehner, lauriii, andypost, xjm: Remove SafeMarkup::escape() and rely more on Twig autoescaping

Issue #2553969 by alexpott, dawehner, xjm: Use \Twig_Markup in twig_drupal_join_filter() since it is part of Twig and should not pollute the safe list

Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender

Revert "Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender"

This reverts commit 9ccb44e2.

Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender

Issue #2407195 by Wim Leers, Fabianx, joelpittet, lauriii, Crell: Move attachment processing to services and per-type response subclasses

Issue #2464045 by fgm: Move twig_render_var/twig_drupal_escape_filter to TwigExtension, inject the renderer in Twig extension and inline render() / show() function instead of calling it

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

Issue #2430981 by Cottser: Unnecessary notices when twig_render_template() catches \Twig_Error_Loader exceptions

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

Issue #2226207 by lauriii, mgbellaire, Cottser, m1r1k, Mark Carver, LinL, rachel_norfolk, rteijeiro, skwashd, davidhernandez, euphoric_mv: Make 'template' the default output option for hook_theme().

Issue #2201789 by joelpittet, jjcarrion, stefanos.petrakis, wiifm, Geizt, lussoluca | Cottser: Don't print '_theme()' in twig_debug output.

Issue #1332068 by Cottser, pixelmord | tim.plunkett: ENGINE_render_template() and ENGINE_extension() are undocumented.

Issue #1825952 by Fabianx, joelpittet, bdragon, heddn, chx, xjm, pwolanin, mikey_p, ti2m, bfr, dags, cilefen, scor, mgifford: Turn on twig autoescape by default

Issue #2227869 by joelpittet: Remove magic printing from Attribute class to make Twig 'without' filter work for attributes.

Issue #2056879 by martin107, Outi, ioskevich, Cottser: Improve twig_* vars DOCs in settings.php and make Twig debug markup require a cache clear.

Issue #2212309 by joelpittet: Drupal\Core\Template and twig.engine docs, coding standards, and unused code cleanup.

Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, alexpott, tstoeckler, Xano, tim.plunkett, BassistJimmyJam | beejeebus: Make modules and installation profiles only require .info.yml files.

Revert "Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, tstoeckler, Xano, tim.plunkett, BassistJimmyJam: Make modules and installation profiles only require .info.yml files."

This reverts commit b4c561d0.

Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, tstoeckler, Xano, tim.plunkett, BassistJimmyJam: Make modules and installation profiles only require .info.yml files.

Issue #2210197 by sun, longwave, Sutharsan: Remove public access to Extension::$type, ::$name, ::$filename.

Issue #2114563 by joelpittet, martin107, Cottser: Remove TwigReference with the help of 'without' filter replacing 'show'/'hide' functions.

Revert "Issue #2210197 by sun, longwave: Remove public access to Extension::$type, ::$name, ::$filename." Broke 'drush en simpletest' on testbots

This reverts commit 2c51074d.

Issue #2029225 by cilefen, Cottser: Twig debug output does not show the base or derived hooks when a theme suggestion is called directly.