Change main runner from fmt to log
Create camera wrapper object to handle top-down entity tracking

This TopDownCamera keeps the Camera given to it exactly on top of the
Entity being tracked at a certain height.
Hook up TopDownCamera to the scene

Had to set up a new hook from Game, BeforeRender, as the Camera position
update must happen after all the rest of the game logic has taken place
to ensure the camera is always exactly where it needs to be.
Add Animation component and behavior

This is my first attempt an a basic Animation structure, where a user
can easily ask for property animations (currently only Position) from
one Position to Another over a given period of time. I want to abstract
out the per-frame logic as much as possible, letting the game code read
well and hiding implementation details.
Use new Animation component and behavior in the game