Began Animal and GUI Implementation

Sitting Birds are alerted by shooting a nearby sitting bird.
Upon being alerted, sitting birds fly away from the bird that was shot.
Shooting a bird makes it explode into feathers and adds a feather
collection item to the GUI. DOES NOT ACTUALLY COUNT COLLECTION YET.
GUI implemented as camera based 3D GUI above the world, facing upwards
to avoid seeing anything that it shouldn't.
Reticle added to GUI as OnGUI() drawn texture.
Elephant Head, Body and Tusk item modelled and imported.