star method

Wanted to learn a little canvas so I refactored an old method from AS3. Tried to follow your conventions and added a demo page.

usage:

ctx.star({
                "x" : Math.random() * ctx.width,
                "y" : Math.random() * ctx.height,
                "points" : Math.round(Math.random() * 20 + 3),
                "innerRadius" : Math.random() * 100,
                "outerRadius" : Math.random() * 100,
                "angle" : 27,
                "fillStyle" : "#" + Math.floor(Math.random()*16777215).toString(16),
                "strokeStyle" : "#" + Math.floor(Math.random()*16777215).toString(16)
            });