Output at least something for unknown node types

[PlasmaHH]

I get quite a few warnings for the builder not supporting some node types, e.g. the built in inheritance_diagram or when using the sphinx.ext.todo extension one todo_node type.

Would it be possible for those not (yet) supported to output something anyways? Like a best effort approach or so, going through the structure and trying to output all other known nodes...

That way it won't look pretty, but at least the information is there.

[liran-funaro]

This can be implemented via a feature flag, which will prevent raising nodes.SkipNode in the method unknown_visit(self, node).
While my bandwidth for implementing new features is limited at the moment, I truly appreciate your initiative and would be happy to review and merge a pull request if you'd like to contribute to this enhancement.