updateAll should pass information to :update() about which state objects have changed

[dphfox]

This would be of specific utility to objects like For* and Spring since these need to disambiguate between different objects updating in order to perform the specific recalculations they need to do. Right now, we have to use inference for springs and fall back on duplicating dependency values for the For* objects.

[dphfox]

We should make sure this doesn't have knock on effects with wider performance among graph objects that don't need to use this information, ideally by making the process of collecting these updated objects as cheap as possible.

[dphfox]

Superseded by #205