Project: foxes-and-rabbits-v2
Authors: Michael Kolling and David J. Barnes

This project is part of the material for chapter 10 of the book

   Objects First with Java - A Practical Introduction using BlueJ
   David J. Barnes and Michael Kolling
   Pearson Education, 2002

A predator-prey simulation involving foxes and rabbits in
an enclosed rectangular field.

This is the second version of the simulation. In this version,
inheritance is used to improve the code structure.

How to start:
    Create a Simulator object.
    Then call one of:
        + simulateOneStep - for a single step.
        + simulate - and supply a number of weeks (say 10) for that many steps.
        + runLongSimulation - for a simulation of 500 weeks.