Issue #2469941 by wadmiraal, jhodgdon: Move database-related hook docs from system.api.php to a new database.api.php file

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

Issue #2414991 by alexpott: Prevent hook_config_schema_info_alter from adding or removing definitions

Issue #2407933 by romina.nayak, adci_contributor, sidharrell, sinniger, arpit_nnd: Move all menu-related hooks and topic to new menu.api.php file

Issue #2225427 by ianthomas_uk, martin107, JeroenT, LoMo: Remove remaining uses of deprecated language functions (mostly in object oriented code)

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 #2322105 by rpayanm, prics, Upchuk, Temoor, seanB, pcambra, jamesdixon: Replace all instances of taxonomy_vocabulary_load(), taxonomy_vocabulary_load_multiple(), entity_load('taxonomy_vocabulary') and entity_load_multiple('taxonomy_vocabulary') with static method calls

Issue #2030669 by daffie, Sharique, rpayanm, Mile23, undertext, marcingy, martin107, filijonka, amitgoyal, msupko: Expand Vocabulary with methods

Issue #2358991 by JeroenT, ianthomas_uk, rpayanm, jamesdixon, er.pushpinderrana, Ashok Negi: Remove usage of drupal_mail()

Issue #2263359 by jhodgdon: hook_help(): Top of page help sections can't link to help pages without a fatal error or checking for help module

Issue #2358999 by rpayanm, JeroenT, er.pushpinderrana, javivf, Ec1ipsis, aczietlow | Les Lim: Remove usage of drupal_html_to_text().

Issue #2307859 by rpayanm, dankh, shumer: Move theme-render hooks from system.api.php to theme.api.php

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

Issue #2028109 by tim.plunkett, almaudoh, twistor, larowlan, slashrsm, Berdir, Arla, neclimdul, Cottser: Convert hook_stream_wrappers() to tagged services.

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 #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 #2343661 by larowlan, tim.plunkett | xjm: Rename l() to _l() and url() to _url(), and document replacements.

Issue #2277103 by tim.plunkett, pwolanin, Wim Leers, dawehner, hotpizzas: Switch Drupal::l() and LinkGenerator to expect a Url object.

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

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

Issue #2038275 by tim.plunkett, mr.baileys, Sam Hermans: Convert hook_queue_info() to plugin system.

Issue #2328411 by dawehner, geerlingguy, herom: Convert all permissions to yml files and permission callbacks.

Issue #2335659 by tim.plunkett, dawehner, effulgentsia, sun: Remove FormState ArrayAccess usage from core.

Issue #2334405 by almaudoh, drunken monkey: Clean up documentation links to functions moved to render element classes

Issue #2313931 by Berdir: Merge ['controller'] with ['build_info']['callback_object'] and add a method for it.