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

Issue #2506445 by joelpittet, Ryan Weal, Sutharsan, alexpott, subhojit777, justAChris, nlisgo, effulgentsia, rpayanm, larowlan, chx, xjm, dawehner, geertvd, lauriii, izus, andypost, borisson_, Sharique: Replace !placeholder with @placeholder in t() and format_string() for non-URLs in tests

Issue #939462 by lauriii, Antti J. Salminen, NROTC_Webmaster, mbrett5062, tim.plunkett, tostinni, rteijeiro, dvessel, cilefen, barraponto, theapi, joelpittet, Xano, tuutti, drzraf, Fabianx, markcarver, xjm, catch, Cottser, sun, jenlampton, effulgentsia, davidhernandez, kscheirer, akalata, andypost, hass, rooby, jhodgdon, fubhy, becw, MXT, mlncn, lemunet, chriscalip, mike stewart, PavanL, kevinquillen, gleroux02: Specific preprocess functions for theme hook suggestions are not invoked

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 #2509300 by dawehner, catch, larowlan: Path alias UI allows node/1 and /node/1 as system path then fatals

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2414255 by lauriii, Jeff Burnz, dawehner, davidhernandez: Subtheme template inheritance working in reverse order

Issue #2151469 by rpayanm, lokapujya, JeroenT, alansaviolobo, Richard Damon, pflame, ianthomas_uk: Clean-up usage of deprecated list_themes() and _system_rebuild_theme_data() in favor of theme_handler service.

Issue #2395395 by alexpott, effulgentsia, Gábor Hojtsy: TestBase lacks a config method to be used consistently in tests

Issue #2362227 by dawehner, mpdonadio, znerol, tim.plunkett, skipyT: Replace all instances of current_path()

Issue #2235901 by alexpott, mdrummond, iMiksu, sun, Wim Leers: Remove custom theme settings from *.info.yml

Issue #2324055 by dawehner, cilefen, znerol: Split up the module manager into runtime information and extension information

Issue #2325571 by asif_khan, omers | dawehner: Replace _theme() calls by calls to \Drupal::theme()->render().

Issue #1530774 by lokapujya, jenlampton, Cottser, svdhout, alexrayu, hpz: Fixed Test coverage for adding classes into region template.

Issue #697760 by sun: Replace getInfo() in tests with native phpDoc + annotations (following PHPUnit).

Issue #1067408 by alexpott, Jalandhar, jessebeach, Désiré, neetu morwani, dawehner, sun: Themes do not have an installation status.

Issue #2011128 by jsbalsera, aboros, Devin Carlson, mr.baileys, pplantinga: Theme_disable() can disable the wrong theme.

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

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 #1886448 by dawehner, sun, Berdir, ParisLiakos: Rewrite the theme registry into a proper service.

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 #2061835 by thedavidmeister, Cottser: Fixed theme() doesn't enforce that what it returns is a string or FALSE.

Issue #2004286 by joelpittet, jenlampton, Cottser, LinL: Defer calls to drupal_get_()* functions until printed inside a template by adding a RenderWrapper class.

Issue #2030457 by Mark Carver, Cottser: Fixed Warning: Missing argument 3 for template_preprocess() for theme functions overridden by templates.