Issue #2849669 by alexpott, pwolanin, Munavijayalakshmi, dawehner: Fix \Drupal\Component\Utility\Unicode() because of the Symfony mbstring polyfill

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

Issue #2281533 by claudiu.cristea, amateescu, tim.plunkett, yched, jibran, catch: Entity Reference default selection plugin ignores matches if an entity type has no label key