fix model run being untitled when started from model loaded from run

The problem was that a model loaded from a run was untitled in the following cases:
* Load a run, switch to Interface tab, click [Setup], come back to Review: new run is untitled. This is because the current NetLogo model has been loaded from a run and there is no .nlogo file associated with it. There is probably a simple way around this.
* Load model A, record a run, load model B, record a run, switch back to A in the run tab, record a new run: new run is "Untitled".