Issue #2463321 by amateescu: Serializing the database connection is dangerous and error-prone, make it unserializable again

Issue #2358079 by pwolanin, Berdir: Require a specific placeholder format in db_query() in order to trigger argument expansion, and require explicit 'IN' parameter for conditions

Issue #2251113 by alexpott, damiankloip, Crell, Wim Leers, dawehner, sun: Use container parameters instead of settings.

Issue #2238649 by visabhishek, bookmarvel, chx: Expirable key value store interface is wrong in comments.

Issue #2182423 by Berdir, joelpittet: Key_value_expire doesn't get reset and balloons the PDO execution time for form pages.

Issue #1786490 by Berdir, amateescu, damiankloip, Wim Leers, dawehner: Add caching to the state system.

Revert "Issue #1786490 by Berdir, amateescu, damiankloip, dawehner: Add caching to the state system."

This reverts commit 8ec847cc.

Issue #2100329 by cosmicdreams: Use \Drupal instead of Drupal to make IDEs and static code analyse tools happy.

This reverts commit 227f21b3.

Issue #512026 by Berdir, effulgentsia, sun, marcingy, Eric_A, xjm, katbailey, Damien Tournoud, alexpott, beejeebus, pillarsdotnet: Move () storage from cache to new state/key-value system.

Issue #1547008 by Berdir, Sutharsan: Replace Update's cache system with the (expirable) key value store.

Issue #1608842 by chx, alexpott, sun, effulgentsia, beejeebus, tim.plunkett et al: Replace list of bootstrap modules, enabled modules, enabled themes, and default theme with config.

Issue #1642062 by tim.plunkett, xjm, chx, merlinofchaos, damiankloip, dawehner, Berdir, aspilicious, Fabianx: Add TempStore for persistent, limited-term storage of non-cache data.

Issue #1175054 by msonnabaum, chx, sun, tim.plunkett, arlinsandbulte, beejeebus: Add a storage (API) for persistent non-configuration state.