Completed Sprite System basics.

Got the sprite system working wonderfully. There is a default
"OnAnimationComplete" method called now that typically just sets the
animation back to doing whatever it was doing before. You can also look
up animations in the manager by name, switch to a given animation by
name, add new animations, and add frames to animations. Frames work by
specifying the position it is on the spritesheet, the time to show it,
and other typical things related to drawing a sprite on screen. By doing
a frame to frame animation system like this, absolute control over the
spritesheet is commanded. Woot!