Issue #1085590 by Rob Loach, keichee, tim.plunkett, mfer, ericduran: Update jQuery UI to the latest in the git repository.

- Patch #1651270 by effulgentsia: remove IE8-specific workaround for lack of CSS3 box-shadow support.

- Patch #1645494 by effulgentsia: Allow core themes to display single-column on IE8: do not compensate for lack of media query support.

Issue #258785 follow-up by Gábor Hojtsy: Added CHANGELOG: Provide more flexible settings for initial language on content types.

Issue #1627208 by vasi1186, Gábor Hojtsy: CHANGELOG: Make language_list() and language_default() return instances of Language.

Issue #1333122 by effulgentsia, tim.plunkett: Clarify docs for theme and preprocess/process functions so it is clearer which ones get called for theme functions vs. templates

- Patch #1262812 by Everett Zufelt, dww, klausi, xjm: make 'Roles' a tab of 'admin/people' instead of 'admin/people/permissions'.

Issue #1635084 by webflo, vasi1186: Added Track import status of files in the locale .po file directory.

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.

Issue #1635134 by hairqles, floretan, webflo: Move date format translation functions from locale to system.

Issue #1637710 by Schnitzel, vasi1186: Fixed Pass on language weight to language_locked_languages() when available.

Issue #1641166 by Schnitzel: Fixed Undefined property: Drupal\Core\Language\Language:: in language_list().

Issue #1640050 by Schnitzel: Fixed Locale summary in language table should be 'not applicable' for locked languages.

Issue #1591686 by greg.1.anderson: Add copyright and authors files to Twig directory and COPYRIGHT.txt

Issue #1596598 by mr.baileys: Mak drupal_goto docs say what happens if path arg is empty, and clarify that on url docs too

Issue #1630264 by vasi1186, fubhy, Gábor Hojtsy: Move field language fallback code from Locale to Field and field language handling for nodes to Node.

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