Issue #1331486 by katbailey, chx, sun, beejeebus, amateescu: Move module_invoke_*() and friends to an Extensions class.

Issue #1253820 by yched, zserno, tim.plunkett, xjm, effulgentsia, plach: Fixed It's impossible to submit no value for a field that has a default value.

Issue #1874300 by Berdir, swentel: Remove $entity_type argument from field.module functions that receive a single $entity.

Issue #1852966 by yched, Stalski, zuuperman, swentel: Rework entity display settings around EntityDisplay config entity.

Revert "Issue #1852966 by yched, swentel: Rework entity display settings around EntityDisplay config entity."

This reverts commit 8ad67af2.

Issue #1852966 by yched, swentel: Rework entity display settings around EntityDisplay config entity.

Issue #1825044 by sun: turn contact form submissions into full-blown Contact Message entities, without storage.

Issue #1763974 by tim.plunkett, EclipseGC, berdir, xjm, neclimdul, FabianX: Convert entity type info into plugins.

Issue #1040790 by yched, swentel, geerlingguy, beejeebus, Berdir: Fixed _field_info_collate_fields() memory usage.

Issue #1696640 by fago, effulgentsia, tim.plunkett, dixon_, plach: Add a uniform Entity Property API.

Issue #1785256 by yched, Stalski, zuuperman, sun, tstoeckler, aspilicious, EclipseGc, larowlan: Widgets as Plugins.

Issue #1700382 by Albert Volkman, cam8001: Replace remaining references to drupal_attributes() with new Attributes().

- Patch #1374030 by aspilicious, Berdir, tim.plunkett: remove entity_extract_ids() now we have proper classed entity objects.

- Patch #1290694 by hefox, tlattimore, c4rl, chx, tim.plunkett, tstoeckler, msonnabaum: provide consistency for attributes and classes arrays provided by template_preprocess().

Issue #1599306 by bojanz, exratione: Fixed field_sync_field_status() needlessly rebuilds module data, slows down installation dramatically.

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 #1552412 by duellj: Make API links point to D8 version, and where possible make them future-proof

- Patch #1404198 by sun, beejeebus, fago, chx: Separate database cache clearing from static cache clearing and data structure rebuilding.

Issue #1302228 by xjm, yched, kathyh, chx, tim.plunkett: Fixed field_has_data() returns inconsistent results – possible data loss.

- Patch #1439692 by clemens.tolboom, plach, dawehner, das-peter, Gábor Hojtsy: Rename field language properties to langcode.