Completed demo with basic 'random' pet

- Example pet currently has 4 variations
- Pet is tamed by right-clicking
- Pet's model / texture changed via right-click with a stick
- Note that each pet can define what item will be used to change models,
but the default is a stick
- Can be told to 'sit' just like other tameable animals, though this is
not currently visible via animation
- Pet will follow owner if not sitting