Element changes are not reported in the changelog

1. Place debugging code in client/query_response.js
2. Make changes to an element, such as the condition code on a rule's LHS
3. Observe how the change is not reported in the changelog

This blocks improvements to marking the model as not unsaved in fewer circumstances.

Start in client/query_response.js and reproduce the issue by changing an element such as a rule LHS condition. Trace how that change is handled for changelog reporting; done means the element change appears in the changelog and supports the stated unsaved-model improvement.

Written by the indexing model from the issue text.