Issue #2329753 by lauriii, davidhernandez, LewisNyman, nathandao: Move html classes from preprocess to templates

Issue #2217731 by crowdcg, lauriii, davidhernandez, aczietlow, jjcarrion, mortendk, karolus, pakmanlh, LewisNyman, aboros, joshua.boltz: Move field classes out of preprocess and into templates

Revert "Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator"

This reverts commit 0bcabf50.

Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator

Issue #2382543 by rpayanm, ianthomas_uk: Remove usage of drupal_html_class() and drupal_clean_css_identifier()

Issue #2226863 by cs_shadow, filijonka, joelpittet, pguillard: Update stale references to theme functions that have been converted to Twig

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

Issue #2346937 by dawehner, larowlan, Wim Leers, claudiu.cristea, msonnabaum: Implement a Renderer service; reduces drupal_render / _theme service container calls

Issue #2370147 by catch, davidhernandez, lauriii: Move is_front variable to template_preprocess_page()

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

Issue #2361681 by Wim Leers: drupal_render(): invert second argument ($is_recursive_call -> $is_root_call) => more strict, better DX/TX.

Issue #2329763 by lauriii, Jens-0, Cottser, Sutharsan: Move links classes from preprocess to templates.

Issue #2329767 by lauriii, alexpott, Cottser, sqndr: Move table classes from preprocess to templates.

Issue #2350949 by Wim Leers: Add hook_page_attachments(_alter)() and deprecate hook_page_build/alter().

Issue #2234331 by mortendk, lauriii, LewisNyman, sqndr, rteijeiro, G-raph, amitgoyal: Fixed Change the body classes to follow Drupal 8 CSS standards.

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().

Issue #2246675 by rpayanm, johnstorey, holly.ross.drupal | mgbellaire: Remove all unnecessary 'template' lines in hook_theme() declarations.

Issue #2070737 by herom, EllaTheHarpy, alexpott: Change values of LanguageInterface::DIRECTION_(LTR/RTL) to ('ltr'/'rtl').

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2346369 by Wim Leers: Support special '#attached' variable for attaching assets in preprocess functions.

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 #2229435 by lauriii, joelpittet, Rade: Clean up the way attributes are printed in field.html.twig.

Issue #2335003 by joshi.rohit100, rootwork, tuutti | joelpittet: Rename task-list.html.twig to maintenance-task-list.html.twig.

Issue #2329771 by davidhernandez, lauriii, pakmanlh: Move image classes from preprocess to templates.

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.

Issue #2343651 by xjm, tim.plunkett, Wim Leers, dinarcon, dawehner: Remove most remaining l() calls.

Issue #1777332 by hass, Cottser, mike.roberts, joelpittet, dawehner | jenlampton: Replace theme_menu_link() and menu-tree.html.twig with a single Twig template.

Issue #2340251 by iMiksu, alexpott, tim.plunkett, dawehner, Wim Leers: Remove most remaining url() calls.

Issue #999338 by lauriii, joelpittet, Sir-Arturio, mgifford, mlncn, alarcombe, sun | Eric_A: Fixed theme_image() alt attribute cannot be passed in $variables['attributes'] .