Clarify hiearchy for animals / pedestrians / humans

In OSC 1.x animals are a certain type of pedestrian as they share most attributes of human pedestrians and most simulators also use the same models to drive them. The domain model proposed in the concept phase divided animals and pedestrians as their combination is counter-intuitive. As of now, the current development state of the domain model does not specifically mention animals. Rather, pedestrians are a sub-class of humans here. We need to clarify the hierarchy of animals vs. pedestrians vs. humans vs. passengers.