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

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 #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 #1792600 by Stalski, fubhy, swentel: Refactor field_ui() so common behavior for fields and display overview screens are extracted.

Issue #1757504 by Maxtorete, boran, c31ck, Gábor Hojtsy: Fixed Regression: language field is not visible on manage display.

Issue #1074672 by claudiu.cristea, boran, tim.plunkett, webflo, Schnitzel, mikewink: Added Allow language select to be rearranged inside node form.

Issue #1711070 by kid_icarus, tim.plunkett, xjm, droplet, zendoodles and cam8001: Convert tests to use ::$modules property instead of parent::setUp($modules).

Issue #258785 by Désiré, Schnitzel, kbasarab, pkiraly, desbeers, Bojhan, voxpelli, clemens.tolboom, Artusamak, Gábor Hojtsy, dvinegla: Added Provide more flexible settings for initial language on content types.