Add support for twig templates

Twig is a very commonly used templating library for PHP. It would be nice if the HTML analyzer understood Twig tags. Currently, these tags can cause errors, for example:

	.doc_manager {
		background-color: {{ systemUser.get('background-color') }}

Will lead to complaints about systemUser.get('background-color') being an ‘unexpected unknown property’, even though it would be properly replaced at runtime.


‘unexpected unknown property’, are we talking about CSS rule here? (you can check that by rule key prefix)

Yes, it’s rule css:S4654