Issue #1053648 by mdrummond, lokapujya, Cottser, Jeff Burnz, Les Lim, Gábor Hojtsy: Convert site elements (site name, slogan, site logo) into blocks.

Issue #2171269 by effulgentsia, Wim Leers, InternetDevels, snig: Handle block rendering's #attributes correctly (fixes in-place editing of custom blocks).

Issue #2130811 by alexpott, Gábor Hojtsy, vijaycs85, sun, Wim Leers: Use config schema in saving and validating configuration form to ensure data is consistent and correct.

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 #1653026 by damiankloip, alexpott, sun, tim.plunkett, dawehner, mtift: Fixed All configuration values are stored as strings.

Issue #2057869 by dawehner, jibran: Provide an alias for 'plugin.manager.entity' called 'entity.manager'.

Issue #1847002 by tim.plunkett, effulgentsia, msonnabaum: Move entity type classes from Drupal$provider\Plugin\Core\Entity to Drupal$provider\Entity.

Issue #1754246 by webflo, swentel, penyaskito, andypost, alexpott, YesCT, dagmar: Languages should be configuration entities.

Issue #1620010 by dawehner, ParisLiakos, plach, jibran: Move LANGUAGE constants to the Language class.

Issue #1898034 by Cottser, jenlampton, joelpittet, Shawn DeArmond, idflood, Hydra, artofeclipse, rich.yumul, chrisjlee, gnuget, c4rl, thund3rbox: block.module - Convert PHPTemplate templates to Twig.

Issue #1927608 by EclipseGc, tim.plunkett, effulgentsia: Remove the tight coupling between Block Plugins and Block Entities.

Issue #1987298 by tim.plunkett, quicksketch: Shorten directory structure and PSR-0 namespacing for plugins.

Issue #1982024 by Cottser, Fabianx: Lazy-load Attribute objects later in the rendering process only if needed.

Issue #1947814 by vijaycs85, Gábor Hojtsy, tim.plunkett: Fixed New config entities often save as langcode: und incorrectly.

Issue #1875260 by Gábor Hojtsy, xjm, brantwynn, EclipseGc, Bojhan: Fixed Make the block title required and allow it to be hidden.

Issue #1935000 by Gábor Hojtsy, vijaycs85: Fixed Some configuration entities are created as in language unknown.

Issue #1591806 by tim.plunkett, ryanissamson, jenlampton, Risse, psynaptic, Gábor Hojtsy, kmcculloch, pakmanlh, Rob Loach: Change block 'subject' so that it's called (admin_)label like everything else on the theme layer.

Issue #1891516 by sun, Berdir, chx: Remove $install parameter from DrupalUnitTestBase::enableModules(), encourage to create individual schema tables only.

Issue #1871696 by tim.plunkett, xjm, sun, msonnabaum, EclipseGc: Convert block instances to configuration entities to resolve architectural issues.