make {"include": "$self"} (optionally) also include parent definitions

When you include a syntax definition that contains spans and therein {"include": "$self"} (e.g. the shell syntax rules), then within such syntax blocks (shell loops) your own syntax rules are not further used.

it would be nice, to have something like

{"include": "source.shell", "propagateSelf": true}

This would then make sure, that each {"include": "$self"} in source.shell would get access also to my tree first.