I'm hoping to get twig support added to the core in concretecms/concretecms#12500 but I can't do that without full support for translations.

I've put together an example of how we might support Twig files using Twig's own lexer and it seems to work pretty well though it might not parse files that make use of custom operators that we don't have implementations for.

I figure this deserves a bit of thought before diving in to. Any direction and feedback is appreciated!