Issue #1845034 by RobLoach, sandykadam, nick_schuch, cam8001, Gábor Hojtsy: Convert standard.inc to Drupal\Core\Language.

Issue #1987066 by Kevin Morse, JohnAlbin, rteijeiro, echoz, ry5n: Rename files to match CSS file naming convention.

This reverts commit c4e52bb6.

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

Issue #1977784 by YesCT, Gábor Hojtsy, EllaTheHarpy: Content language settings configuration page needs to determine what entities and bundles to include.

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 #1822458 by tim.plunkett, effulgentsia: Move dynamic parts (view modes, bundles) out of entity_info().

Issue #1810386 by plach, YesCT, Bojhan, bforchhammer, Gábor Hojtsy, falcon03: Create workflow to setup multilingual for entity types, bundles and fields.

Issue #882666 by mgifford, andrewmacpherson, sun: Fixed Core form descriptions shouldn't use a label when not associated with a form.

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

Issue #1714462 by n3or, sun, Gábor Hojtsy: Convert language negotiation settings to configuration system.

Issue #1480854 by tim.plunkett, Noyz, Bojhan, yoroy, kika: Convert operation links to '#type' => 'operations'.

Issue #365615 by attiks, smokris, penyaskito, Gábor Hojtsy, Bojhan, WormFood, yang_yi_cn: Fixed Language detection not working correctly for most Chinese readers.

Issue #1751082 by das-peter: Fixed Undefined index: langcode in language_admin_edit_form_validate().

Issue #1738330 by k4v, das-peter, jsbalsera, bforchhammer, Schnitzel: confusing Language negotiation when accessing /.

Issue #1739994 by pp, das-peter, Gábor Hojtsy: Use the Language class universally instead of stdObj instances.

Issue #1738374 by sxnc, Gábor Hojtsy: Provide a cue to enable the language switcher when adding a language.

Issue #1471432 by Gábor Hojtsy, vasi1186, tobiasb, kalman.hosszu, Schnitzel, nod_, pixelite, dawehner: Rework language_list(), let people use more special languages.

- Patch #1627498 by webflo, Rob Loach: Fixed Undefined variable  in language_admin_add_predefined_form_validate().

- Patch #1587850 by pfrenssen, chrisdolby: replace drupal_not_found() with throw NotFoundHttpException.

- Patch #1183208 by effulgentsia, Niklas Fiekas, katbailey, no_commit_credit, catch: remove variable_get()('clean_url()') and switch to index.php/path pattern for dirty URL support.

- Patch  #1468930 by dawehner, Gábor Hojtsy, plach, das-peter, fubhy: clean up and move the code for the negotiation functionality from locale module to language module.

Issue #1301040 by Gábor Hojtsy: Move language listing functionality from locale.module to a new language.module.