Issue #2028025 by David Hernández, Berdir, larowlan, ceng, YesCT, a_thakur: Expand CommentInterface to provide methods.

Issue #2078387 by Xano, andypost, twistor, splatio, InternetDevels, amateescu, Berdir, larowlan, vladan.me: Add an EntityOwnerInterface.

Issue #2080577 by mrsinguyen: Remove Unused local variable  from /core/modules/comment/lib/Drupal/comment/Tests/CommentTokenReplaceTest.php.

Issue #731724 by larowlan, andypost, dixon_, tsvenson: Convert comment settings into a field to make them work with CMI and non-node entities.

Issue #1754246 by webflo, swentel, penyaskito, andypost, alexpott, YesCT, dagmar: Languages should be configuration entities.

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

Issue #1801304 by Amitaibu, amateescu, effulgentsia, tim.plunkett, EclipseGc, Fabianx, Cottser: Added Entity reference field.

Issue #1778178 by fago, Berdir, effulgentsia, mradcliffe, das-peter: Convert comments to the new Entity Field API.

Issue #1305378 by bforchhammer, penyaskito, k4v, Schnitzel, Gábor Hojtsy, Dave Reid: Added Tokens should use $options["langcode"] and not need a language object.

Using the language_manager wrapper function to return a language whether or not we're in the requet scope

- Patch #1510686 by cosmicdreams, vasi1186, webflo, disasm: replace remaining references to global () with drupal_container().