Issue #2025991 by plach, David Hernández: Introduce hook_entity_prepare() to generalize hook_node_prepare().

Issue #111715 by andypost, swentel, tim.plunkett, sun, Berdir, amateescu, kkaefer, YesCT, dagmar, chx: Convert node/content types into configuration.

This reverts commit c4e52bb6.

Issue #1498674 by plach, das-peter, Schnitzel, dawehner, YesCT, attiks, Berdir, Gábor Hojtsy, Soul88, Carsten Müller: Refactor node properties to multilingual.

Issue #1620010 by dawehner, ParisLiakos, plach, jibran: Move LANGUAGE constants to the Language class.

Issue #1913618 by tim.plunkett, amateescu: Convert EntityFormControllerInterface to extend FormInterface.

Issue #501428 by KarenS, swentel, tim.plunkett, webchick, effulgentsia, nod_, scor, Lars Toomre: Added Date and time field type in core.

Issue #1838156 by ry5n, swentel, sannejanssen: Implement the two-column layout for the new create content page.

Issue #1838114 follow-up by swentel, sun: Move styling to an alter hook off of Seven theme + other clean-ups.

Issue #1807776 by plach, Berdir, YesCT, Gábor Hojtsy, bforchhammer, Bojhan, webchick: Support both simple and editorial workflows for translating entities.

Issue #1751606 by swentel, ry5n, mrfelton, nod_, sun, sannejanssen: Move published status checkbox next to 'Save'.

Issue #1356170 by ohnobinki, tim.plunkett: Remove all uses of array_merge_recursive(), or document why they are being used instead of NestedArray::mergeDeep().

Issue #1852966 by yched, Stalski, zuuperman, swentel: Rework entity display settings around EntityDisplay config entity.

Revert "Issue #1852966 by yched, swentel: Rework entity display settings around EntityDisplay config entity."

This reverts commit 8ad67af2.

Issue #1852966 by yched, swentel: Rework entity display settings around EntityDisplay config entity.

Issue #1168246 by sun, mgifford, Manuel Garcia, mbrett5062, ry5n, Everett Zufelt, nod_, aspilicious, deviantintegral, tim.plunkett: Freedom For Fieldsets! Long Live The DETAILS.

Issue #1188388 by plach, peximo, YesCT | Gábor Hojtsy, fago, webchick, Bojhan, podarok, cosmicdreams, Berdir, aspilicious, bforchhammer, penyaskito: Added Entity translation UI in core.

Issue #1739928 by vasi1186, YesCT, webflo, Transition, plach, Gábor Hojtsy: Generalize language configuration on content types to apply to terms and other entities.

Revert "Issue #1588422 by andypost, disasm, sun, dawehner, vasi1186, alexpott, tim.plunkett, larowlan, Gábor Hojtsy: Convert contact categories to configuration system."

This reverts commit 5cb63c4d.

Oops. That was a little more patch than we bargained for. :P

Issue #1588422 by andypost, disasm, sun, dawehner, vasi1186, alexpott, tim.plunkett, larowlan, Gábor Hojtsy: Convert contact categories to configuration system.

Issue #1723892 by Berdir, Pancho, das-peter, fago: Support for revisions for entity save and delete operations.

Issue #1498874 by peximo, plach, Gábor Hojtsy, attiks: Provide language awareness to entity forms (introduce the form language concept).