Cameras are used to display the 3D world. You can manage them like real life
cameras, which means you can rotate, move, change the field of vision and more.
At least one camera is absolutely required in order to render the world to the
screen. Many cameras can be used at the same time with different positions
and views to allow cool effects like: split-screen, rear view, etc.
InitEngine3D() must be called successfully before using the
camera commands.
