ReporterLogoThunk

This is used by SliderConstraint. Sliders have snippets of Logo code associated with them, which need be to be evaluated to produce numbers for the min, max, and increment. But here in the org.nlogo.agent package we don't know anything about Logo code and how to run it. This interface lets other code keep us in the dark by giving us a black box that magically produces an object whenever we ask for one. (In the case of SliderConstraint the object should be a boxed double.)