public void addRenter(PersonAgent rp) {
   ResidentAgent r = new ResidentAgent("renter " + renters.size(), type, renters.size());
   r.setHousing(this);
   panel.addRenter(r, type, renters.size());
   renters.add(new Renter(r, rp, renters.size()));
 }
 public void addRenter() { // hack
   ResidentAgent r = new ResidentAgent("renter " + renters.size(), type, renters.size());
   r.setHousing(this);
   panel.addRenter(r, type, renters.size());
   renters.add(new Renter(r, null, renters.size()));
 }