Issue #1728804 by Berdir: Introduce (Content)EntityDeleteForm and children to handle entity deletions

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

Issue #2322233 by Temoor, Mirroar, estoyausente: Replace all instances of user_role_load(), entity_load('user_role') and entity_load_multiple('user_role') with static method calls.

Issue #2202185 by Wim Leers, effulgentsia, msonnabaum, damiankloip, alexpott: Statically cache Role entities to speed up (User|UserSession)::hasPermission().

Issue #2030655 by justafish, Alumei, daffie, alexpott, wwhurley, jamesquinton, pcambra, InternetDevels, rdatar, james_kerrigan: Expand Role with methods.

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

Issue #2286681 by alexpott, tim.plunkett: Fixed Make public properties on ConfigEntityBase protected.

Issue #216064 by Xano, idflood, drifter, Artusamak, ygerasimov, sun, ParisLiakos, Cottser, TravisCarden, marcingy, floretan, catch, tedbow: Entity form "Delete" button triggers server-side + HTML5 form validation; change "Delete" button to a link.

Issue #2166915 by ianthomas_uk, sun | plach: Remove uses of deprecated language functions in tests and procedural code.

Issue #2135975 by larowlan, dawehner, a_thakur: Regression: Second level tabs for Permissions and Roles missing from admin/people/permissions and admin/pages/permissions pages.

Issue #2074037 by Wim Leers, effulgentsia: Add drupalPostUrl() — drupalPost()/drupalPostAjax() are for forms only, D8 JS performs non-form HTTP requests.

Issue #1754246 by webflo, swentel, penyaskito, andypost, alexpott, YesCT, dagmar: Languages should be configuration entities.

Issue #1947814 by vijaycs85, Gábor Hojtsy, tim.plunkett: Fixed New config entities often save as langcode: und incorrectly.

Issue #1479454 by Hugo Wetterberg, galooph, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun, dawehner: Convert user roles to configurables.

Revert "Issue #1479454 by Hugo Wetterberg, galooph, dawehner, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun: Change notice: Convert user roles to configurables."

Broke testbot. :(

This reverts commit 2ae15972.

Issue #1479454 by Hugo Wetterberg, galooph, dawehner, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun: Change notice: Convert user roles to configurables.

- Patch #1262812 by Everett Zufelt, dww, klausi, xjm: make 'Roles' a tab of 'admin/people' instead of 'admin/people/permissions'.