The _createHere function is fundamentally impure

Summary: The function works fine, mind, but it's potentially a bad camel's nose in the tent. Can we come up with a pure way to accomplish the same goal?

That is, _createHere as currently structured is side-effecting. It is the only side-effecting function in Querki (I think), and thus automatically a bad smell.

The question is, can we redefine this in a way that is not side-effecting? The UX goal is pretty specific: I want to be able to define a QL expression that creates a new Thing based on a given Model, eventually with specific Properties, and render it immediately. Can we restructure the approach to that goal to be pure?

This may become a more important problem going forward, as we try to do more imperative stuff in response to button-presses and suchlike, so it's time to think through the approach more carefully.