coordinate system changes

*(0,0) is now the center of the screen
*Rectangle objects
*Sprite objects
*Functions can usually figure out what you mean even if you don't give
an actual point, rectangle, etc
*Lots of other changes
title change
new Rect-based screen system

*Drastic changes to Rect object
*DrawStringBox method
*Changed some function arguments
*Nstring object to represent strings formatted into lines
*Fixed fill function