Add lots of Fiesta core
Add lots of Fiesta core

This is a large commit! Let's break it down...

- Fiesta.GameObject: these are any objects that are part of the
  game. Expect them to be turned into Fiesta.PhysicalGameObject;
  this differentiates between "helper" objects and actual objects
  that are visible.

- Fiesta.Sprite: these are 2D sprites, to be displayed on a 2D
  playground. They can be animated.

- Fiesta.Sound: these are sounds. Right now, there is only one
  method (other than the constructor): play(). In the future, there
  will be more.

- Fiesta.Playground: Playgrounds are where the game actually happens;
  all game objects are there, and these are (usually) shown to the
  player.

- There are some other functions at the end; semi-real GUIDs, sprite
  preloading, degree/radian conversion, and point distances.

Keep in mind that a lot of this will change!

EvanHahn/Fiesta.js