Needs more discussion.

This reverts commit b983fad1.

Issue #2330899 by attiks, Jelle_S, fietserwin: Allow image effects to change the MIME type + extension, add a convert image effect.

Issue #2341385 by damiankloip: Fixed No alter hooks are invoked for views handler plugin definitions.

Issue #2350877 by dawehner, Wim Leers, hussainweb: Deprecate/rename drupal_add_feed(), drupal_add_html_head(), drupal_add_html_head_link(), drupal_add_http_header(), and allow to be set declaratively in #attached.

Issue #2331113 by David_Rothstein: Fixed Node access rebuilds are completely broken when being rebuilt through a batch process?.

Issue #2350997 by SchnWalter: Fixed Help module install error when Taxonomy is disabled because of Field UI.

Issue #2246675 by rpayanm, johnstorey, holly.ross.drupal | mgbellaire: Remove all unnecessary 'template' lines in hook_theme() declarations.

Issue #2350571 by mitrpaka: Replace extend of deprecated DrupalUnitTestBase with KernelTestBase in Field.

Issue #2320277 by jhodgdon: Fixed Views comment language field/filter is for original language code, no translation language field/filter.

Issue #2184907 by JeroenT, ParisLiakos, ianthomas_uk, hussainweb, dawehner: Remove uses of drupal_add_http_header and related functions.

Issue #2070737 by herom, EllaTheHarpy, alexpott: Change values of LanguageInterface::DIRECTION_(LTR/RTL) to ('ltr'/'rtl').

Issue #2273825 by rpayanm, dawehner: Fixed UserStorageInterface should extend EntityStorageInterface.

Issue #2293899 by leon.nk, nlisgo: Fixed hook_views_preview_info passes an instance of ViewsUI instead of ViewExecutable.

Issue #2158571 by tstoeckler, dawehner, kgoel, chx, tim.plunkett, catch, effulgentsia: Fixed Followup: Routes added in RouteSubscribers cannot be altered.

Issue #2336199 by benjy, tstoeckler, ultimike: Added Allow to specify the database target for a specific migration.

Issue #2348547 followup by larowlan: Fixed CommentViewBuilder should use static where possible, subclassing is currently too painful.

Issue #2342683 by David Hernández, dawehner: Fixed NodeViewBuilder should use static where possible, subclassing is currently too painful.

Issue #2319667 by aneek, vurt, dankh: Fixed Simpletest Module Double escaped HTML in hook_requirements.

Issue #74562 by naxoc, eiriksm, mikemiles86 | llizards: Added Show keywords in title of search results page.

Revert "Issue #2349651 by yannisc, larowlan: Fixed Default contact form does not send email as email recipient is not set during the installation."

This reverts commit 62f8b460.

Issue #2349651 by yannisc, larowlan: Fixed Default contact form does not send email as email recipient is not set during the installation.

Issue #2322037 by oenie, Temoor, jepSter, rpayanm: Replace all instances of responsive_image_mapping_load(), entity_load('responsive_image_mapping') and entity_load_multiple('responsive_image_mapping') with static method calls.

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2322067 by Temoor, ashutoshsngh, roderik, finn.lewis: Replace all instances of taxonomy_term_load(), entity_load('taxonomy_term') and entity_load_multiple('taxonomy_term') with static method calls.

Issue #2318377 by dawehner, Wim Leers, damiankloip: Determine whether a view is cacheable and its required contexts, store this i/t config entity.

Issue #2346369 by Wim Leers: Support special '#attached' variable for attaching assets in preprocess functions.

Issue #2028053 by vegantriathlete, franxo, InternetDevels, thamas, rootwork, LewisNyman: Add typographic styles, components, and utility classes.