TODO

1. Save data as images
2. Donot crash if ball goes out
3. Allow arbitray wall configuration
4. Allow 2 Balls

#Why one ball goes inside the other?
A: Because, the intersection point is measured along the heading direction, but when a "finite" size ball   collides with a surface it is not the point along the heading direction on the ball that collides 
	 first, but the point that touches the wall first. For, eg if the ball is moving diagonally towards
	 the bottom wall, then the lowermost point of the ball will first collide the surface! My code
	 doesnot account for this.