Issue #2826404 by mpdonadio, Jo Fitzgerald, jhedstrom, larowlan: Create DateTimeItemInterface and deprecate global constants in datetime.module

Issue #2830094 by mpdonadio, Yogesh Pawar, arunkumark, jhedstrom, larowlan, alexpott: Deprecate and remove usages of datetime_date_default_time()

Issue #2829845 by mpdonadio, Jo Fitzgerald, xjm, jhedstrom: Record timezone in DateTime test assertions and verbose output

Issue #2486019 by mpdonadio, pfrenssen, webflo, michielnugter, maris.abols, ivanjaros, hauruck, MickeA, Jo Fitzgerald, mian3010, iMiksu: Wrong validation messages in Datelist::validateDatelist()

Issue #2780063 by mpdonadio, Jo Fitzgerald, GoZ, boaloysius, klausi, Lendude: Convert web tests to browser tests for datetime and datetime_range modules

Issue #2858625 by mpdonadio: Daterange formatters should use $date->getTimestamp() instead of $date->format('U')

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #1918994 by Tim Bozeman, mgifford, mpdonadio, vprocessor, sun, xjm, falcon03, nabiyllin, rteijeiro, cwarsaw, yoroy, andymartha, jessebeach, lauriii, jhedstrom, andypost, Bojhan, cilefen, aaronbauman, sugaroverflow: Improve Datetime and Daterange Widget accessibility

Issue #2775669 by jhedstrom, denutkarsh, xjm, mpdonadio: Clean up redundant methods in datetime field formatters

Issue #2796145 by mpdonadio, kunal.kursija, Gábor Hojtsy, jhedstrom, hass: Daterange field labels not specific enough

Issue #2811725 by mpdonadio, paulanders, jhedstrom: Error when render Datetime Range field: Error: Unsupported operand types

Issue #2796151 by mpdonadio, jhedstrom, myLies, vijaycs85, lomasr, alexpott, Gábor Hojtsy, penyaskito, catch, xjm: Date range separator should be translatable

Issue #2786583 by claudiu.cristea, jhedstrom, effulgentsia: Create a base class for DateTimeFieldTest and DateRangeFieldTest and move common code into it

Issue #2161337 by mpdonadio, darrick, swentel, effulgentsia, YesCT, xjm, Berdir, tim.plunkett, pguillard, SKAUGHT, sylus, jonathanjfshaw, FluxSauce, DuneBL, jhedstrom, dawehner, generalredneck, pjonckiere, borisson_, Gábor Hojtsy, webchick, miwayha: Add a Date Range field type with support for end date