Issue #1596472 by catch, amateescu, claudiu.cristea, Berdir, Mile23, Sam152, pounard, fago, alexpott, fubhy, hchonov: Replace hard coded static cache of entities with cache backends

Issue #2804525 by shashikant_chauhan, joachim: EntityTypeManager should mention hook_entity_type_build()

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2626548 by dawehner, slashrsm: The static caching in \Drupal\Core\Entity\EntityTypeManagerInterface::getFormObject() is problematic

Issue #2337191 by tim.plunkett, dawehner, jibran, yched, Wim Leers, catch: Split up EntityManager into many services