Generalize "Unification"

[giltho]

Right now, we support a "unification" request. It would be great to find a practical example of another kind of operation happening that would be visualized in the same way.
Basically "unification" is just another panel corresponding to a sub-trace of one node?

[NatKarmios]

At least for the way we use it, the state update event could just supply that map whenever the main exec is on a node with unifications. Currently the frontend caches them, but it's not really necessary.