This reverts commit 172318fb.

Issue #1763640 by beejeebus, alexpott, Jose Reyero, c31ck, das-peter, YesCT, heyrocker, Gábor Hojtsy: Introduce config context to make original config and different overrides accessible.

Issue #1784784 by beltofte: Standardize capitalization on actions, in aggregator: 'update items', 'remove items'.

Issue #1889620 by vijaycs85, sun, heyrocker: Fixed config_install_default_config() overwrites existing configuration.

Issue #1904404 by tim.plunkett: Fixed HEAD BROKEN Update EntitySerializationTest to reflect actual Serializer setup.

Issue #1804380 by miro_dietiker, vijaycs85, 8thom, swentel: Convert color variables to config/state.

Issue #1904404 by damiankloip, linclark: Fixed Update EntitySerializationTest to reflect actual Serializer setup.

Issue #1904214 by vijaycs85: Fixed Installer auto-selects languages that don't have a translation, causing a requirements error.

Issue #1891516 by sun, Berdir, chx: Remove $install parameter from DrupalUnitTestBase::enableModules(), encourage to create individual schema tables only.

Issue #1914366 by vijaycs85, Gábor Hojtsy, alexpott: Move all configuration schema files into a schema subdirectory.

Issue #1910318 by katbailey: Make path resolution the responsibility of a series of PathProcessor classes, rather than one PathSubscriber class.

Issue #1906506 by Fabianx, steveoliver, Cottser: Added Twig settings implementation: Show theme hook / template suggestions in HTML comments.

Issue #494518 by c4doug, edrupal, Rob C, a_thakur, YesCT, mcrittenden: Added Allow for custom user registration approval email address.

Issue #1807692 by plach, YesCT, yched: Added Introduce a column synchronization capability and use it to translate alt and titles through the image field widget.

Issue #1515312 by heyrocker, beejeebus, alexpott, xjm, realityloop, sun: Added snapshots of last loaded config for tracking whether config has changed.

Issue #1809352 by nick_schuch, larowlan, jthorson, Wim Leers, Devin Carlson, effulgentsia, tim.plunkett, jessebeach | cweagans: Added Write tour.module and add it to core.