Add spin to collision and update AI
Add spin to collision and update AI

Spins now cause the ball to change direction slightly when colliding. AI
has been updated to 'aim' ahead of the ball but its aim is damaged by
the spin (to make it more error-prone to spins). Opponent's paddle's
maximum speed has also been drastically reduced as the AI is more
intelligent.

Hapaxia/MyPracticeBeginnerGames