Issue #2014895 by Wim Leers, jessebeach: Image captions & alignment.

core/modules/filter/css/filter.caption.css

core/modules/filter/filter.module

.../filter/lib/Drupal/filter/Plugin/Filter/FilterCaption.php

...modules/filter/lib/Drupal/filter/Tests/FilterUnitTest.php

core/modules/filter/templates/filter-caption.html.twig

core/profiles/standard/config/filter.format.basic_html.yml

core/profiles/standard/config/filter.format.full_html.yml

core/themes/bartik/css/style.css