Issue #2045931 by PerthSam152, LinL, adsw12, joelpittet: Replace all module_exists() deprecated function calls.

This reverts commit cc84f390 - bad
commit message.

Issue #2060705 by yched, Hydra, swentel, amateescu: Remove the 'hidden widget' plugin, it is actually never used.

Issue #2063671 by kim.pepper, ParisLiakos, LinL: Use the aggregator category storage in AggregatorCategorizeFormBase.

Issue #2047227 by StephaneQ, SeanKelly, richardj: Update templates to leverage support for the Twig {% trans %} tag extension.

Issue #2077387 by wadmiraal, guschilds: Fixed Taxonomy term is improperly deleted when only one of two parents is deleted.

Issue #2014017 by jlbellido, alvar0hurtad0, undertext, benjy, penyaskito, LinL: Replace drupal_container() with Drupal::service() in the system module.

Issue #2057203 by olli: Fixed Unable to select the 'Default' view mode in views entity area handler.

Issue #2046245 by Mile23, jhedstrom, dawehner: Expand phpunit tests for \Drupal\Component\Utility\Url.

Issue #2043527 by tim.plunkett, vijaycs85, dawehner: Fixed Theme name is included in block machine name but should be stored as a key instead.

Issue #2089631 by Wim Leers | jessebeach: Fixed Showing/hiding of CKEditor plugin settings is fragile, automate it (breaks in narrow viewports and when enabling CKEditor).

Issue #2108955 by Wim Leers: Fixed Settings for disabled filters are not hidden in narrow viewports, because Vertical Tabs are disabled in narrow viewports.

Revert "Issue #2089631 by Wim Leers | jessebeach: Fixed Showing/hiding of CKEditor plugin settings is fragile, automate it (breaks in narrow viewports and when enabling CKEditor)."

This reverts commit 46db1365.

Issue #2004878 by kalabro, DmitryDrozdik, YesCT: Config page title 'Content language settings' misleading after translation is enabled.

Issue #2072533 by swentel: Group together 'Decimal', 'Float' and 'Integer' in the field type drop-down menu.