SpotlightJS shows a spotlight over a Web page.
It can create a transparent canvas on the top of the Web page with a dark area and a light
rounded spot area which make the content below it appear as if it highlighted by a spotlight.
The spotlight can be animated so it can move at a given speed.
Callback functions may be invoked when the user drags the mouse over or clicks in the
spotlight or the canvas area,
as well when the animation starts and ends.
