Revert "Issue #2241633 by sun: Simplify site-specific service overrides."

This reverts commit c5c075dfd8b3d71a6a3a3c2c926ab1ba7bc9c9ce.
Revert "Revert "Issue #2241633 by sun: Simplify site-specific service overrides.""

This reverts commit ecf2fa7296d0640088c6bbf3a8fd7f3459d6a28c.
Issue #2116363 by Berdir, jessebeach | fago: Unified repository of field definitions (cache + API).
Issue #2256355 by tim.plunkett: Make block plugins usable outside the block entity context.
Issue #2261401 by Berdir: Automatically provide bundle info/list based on bundle_of annotation.
Issue #2258299 by juampy: Dblog_menu_link_defaults_alter() must set 'machine_name' to avoid duplicates.
Issue #2268439 by Gábor Hojtsy: String introspection backwards data typing is confusing / incorrect.
Issue #2266859 by tim.plunkett: Move the dependency calculation helper methods from ConfigEntityBase to generic traits.
Issue #2267763 by pwolanin, tim.plunkett: Page titles with %placeholders are broken when used as breadcrumbs.
Issue #2266377 by dawehner, bkosborne, pwolanin: Speed up UrlGenerator a little by setting the 'external' option in the Url object  .
Issue #375062 by cs_shadow, juampy, theunraveler, mondrake, hswong3i, smk-ka: Imagecolorsforindex() Color index nnn out of range in GDToolkit.
Issue #2222719 by effulgentsia, tim.plunkett, xjm, dawehner: Use parameter matching via reflection for access checks instead of pulling variables from request attributes.
Issue #2262861 by alexpott: Add concept of collections to config storages.
Issue #2254183 by sun, tim.plunkett: Fix test performance of Drupal\filter\Tests\FilterAdminTest.
Issue #2265977 by olli: fixed php backend serialization.
Issue #2266501 by Gábor Hojtsy, vijaycs85, YesCT: Array level schema errors are not reported, fix wrong schemas identified.
Issue #1807662 by sun, beejeebus, damiankloip, Wim Leers, Mixologic: Built-in APCu support in core (PHP 5.5 only).
Issue #2253109 by ParisLiakos: Bring .htaccess and web.config up to date.
Issue #2263351 by jcisio: Replace accidentally removed part of default.settings.php.
Issue #2223423 by Xano, tim.plunkett: Stop extending \Drupal\Core\Entity\Entity in unit tests.