Made progress toward fixing "trailing ball" Issue

This line(148) of code:
 var contactAngle = -Math.atan2(contactVecY, contactVecX);
was corrected to:
var contactAngle = -Math.atan2(contactVecY, contactVecX);
because tan is opposite over adjacent, not the other way around. This
fixes the cue ball(mostly), but not for other balls