function polygonDecomp(polygon){
    var edges = polygonGetCutEdges(polygon);
    if(edges.length > 0){
        return polygonSlice(polygon, edges);
    } else {
        return [polygon];
    }
}
Decomposes the polygon into one or more convex sub-Polygons.
@method decomp
@return {Array} An array or Polygon objects.