Improved collision

Ouch, collision is a very hairy topic!
I've implemented countless versions but whatever was working in Classic mode had problems in Modern mode and vice versa.
This is because in Classic I'm using just rectancles for the paddles and ball too and in Modern using a circle for the ball.
The problem was cause by the fact that "X" coordinate is in the center for the circle and top left for the rectangle.

I wish I had some solution for the pad movement jerkyness...