Issue #2462393 by stefan.r, joelpittet: Upgrade Twig to 1.18.1 from 1.18.0

core/composer.lock

core/vendor/composer/installed.json

core/vendor/twig/twig/.travis.yml

core/vendor/twig/twig/CHANGELOG

core/vendor/twig/twig/composer.json

core/vendor/twig/twig/doc/api.rst

core/vendor/twig/twig/doc/deprecated.rst

core/vendor/twig/twig/doc/installation.rst

core/vendor/twig/twig/doc/recipes.rst

core/vendor/twig/twig/ext/twig/php_twig.h

core/vendor/twig/twig/ext/twig/twig.c

core/vendor/twig/twig/lib/Twig/Autoloader.php

core/vendor/twig/twig/lib/Twig/Environment.php

core/vendor/twig/twig/lib/Twig/Error.php

core/vendor/twig/twig/lib/Twig/Extension/Core.php

core/vendor/twig/twig/lib/Twig/Loader/Filesystem.php

core/vendor/twig/twig/lib/Twig/Loader/String.php

core/vendor/twig/twig/lib/Twig/Node/Embed.php

core/vendor/twig/twig/lib/Twig/Node/Expression/Call.php

core/vendor/twig/twig/lib/Twig/Node/Expression/Name.php