A special type of actor that takes on elliptical bounds.
base:Another Actor upon which to 'base' this one (in the scene graph). A properly implemented jStage game will use a jStage.Stage as the base of the scene graph, so this parameter should not be null or undefined.
points:The number of vertices to use in constructing the ellipse. Higher is more 'circular', lower is faster.
xrad:The radius of the ellipse along the x-axis.
yrad:The radius of the ellipse along the y-axis.