Issue #2293501 by dawehner, Wim Leers, znerol: Use route name and params instead of _system_path in CsrfAccessCheck.
Issue #2254181 by Wim Leers, Arla, blueminds, cbr: Fixed Comment indentation is incorrect for comments following a replying-comment: don't render cache comments for which threading is enabled.
Issue #2343607 by alexpott, dawehner: Cleanup UrlGenerator.
Issue #2228125 by dawehner: 'base theme' property in theme .info.yml files does not need to be wrapped in quotes