Issue #2224553 by longwave, swentel: Add _admin_route for field manager and admin/content.
Issue #2218955 by sun: Install_profile_info() removes required module instead of profile module from dependencies.
Issue #2026431 by YesCT, dawehner, Crell: Make ContentNegotiation a 'internal' service, used only by the router, so that core or contrib can implement real negotiation.
Issue #2211553 by andypost, Berdir: Allow usage of entity_reference field widget and formatter for base fields.