Introduce stack-trace function

[borkdude]

Introduce stack-trace function that gives stack trace similar to what is on exception but without throwing exception.

We might be able to do this by keeping references from nodes to parent nodes.

The stack-trace function would then be able to calculate the trace from its own node all the way to the top. It might have to be a special form.

The way we could do this. Keep track of node locations globally in the context. Then use ids to set parents.

;; node-id 101
;; *last-parent-id* 101
;; children: `(->Node ... ... *last-parent-id*)` ;; 101 = parent-id, stack-trace can look up parent-id in global registry in ctx
;; (set-node-id node 101)