Show converging bounds with interval iteration

At the moment, we only show the width of the converging bounds. We should display the converging bounds themselves too.

With this feature, a user can get an impression where the value is converging to.

Imagine a user is making a model, adds a property and observes it's converging to 400 while it should converge to 4. In this case, the user knows something is wrong before full conversion has been reached and can end the checking prematurely.