Issue #2454649 by Aki Tendo, dawehner: Cache Optimization and hardening -- [PP-1] Use assert() instead of exceptions in Cache::merge(Tags|Contexts)

Issue #2336627 by amateescu, Berdir, swentel: Deadlock on cache_config (DatabaseBackend::setMultiple())

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #1923406 by stefan.r, yannickoo, catch, Crell, amateescu, pwolanin, morgantocker, Damien Tournoud, sun: Use ASCII character set on alphanumeric fields so we can index all 255 characters

Revert "Issue #1923406 by stefan.r, yannickoo: Use ASCII character set on alphanumeric fields so we can index all 255 characters"

This reverts commit ac4e35ce.

Issue #1923406 by stefan.r, yannickoo: Use ASCII character set on alphanumeric fields so we can index all 255 characters

Issue #2443651 by alexpott, mradcliffe, bzrudi71: PostgreSQL: Fix system\Tests\Cache\DatabaseBackendUnitTest

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 #2340123 by Wim Leers: Setting cache tags can be tricky: use strings instead of nested arrays to improve DX.

Issue #2224847 by pwolanin, damiankloip, danblack, Berdir: Fixed Automatically shorten cid's in Cache\DatabaseBackend and PhpBackend.

Issue #1167248 by Berdir, damiankloip, Alan Evans, beejeebus, catch: Add CacheBackendInterface::setMultiple().

Issue #2181289 by mradcliffe: Prevent exceptions on missing cache table during cache clear for pgsql.

Issue #2169447 by damiankloip, sun, longwave: DX: Supply CacheBackendInterface::CACHE_PERMANENT as Cache::PERMANENT.

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

Issue #1167144 by chx, catch, claudiu.cristea: Make cache backends responsible for their own storage.

Issue #1764474 by Berdir, chx, alexpott, pounard, msonnabaum: Make Cache interface and backends use the DIC.

Issue #1792536 by chx, Berdir, sun, David_Rothstein: Remove the install backend and stop catching exceptions in the default database cache backend.