Issue #2098795 by tim.plunkett, Sean Charles, tstoeckler, dawehner, larowlan, damiankloip: Create Base Class for RouteSubscriber Class.

Issue #1843752 by joelpittet, Sean Charles: Convert views/templates/views-view-grouping.tpl.php to twig.

Issue #1898454 by c4rl, gnuget, Hydra, mr.baileys, Sean Charles, joelpittet: system.module - Convert PHPTemplate templates to Twig.