Entanglement

The entanglement implementation in master is exponential since we store eset information directly on the var. So if you have 9 vars in an entangled var set (eset) one call to update-dom will trigger a lot of unnecessary computation.

A better implementation would store entangled var sets elsewhere. Then we have to consider data structure representation. We can't quite do what we do with the constraint store becaues of two vars that belong to two different esets become entangle we need to merge the esets together. This means a lot more updating that we have to do with the constraint store. We could maybe represent merges by changing the graph? If there are many merges than lookup would be slow.

We should examine nominal quines to see exactly what happens to esets. We already now they grown large quickly.