public function Circle
Prototype:
public function Circle(x,y,r, filled=false);
Parameters
x
the x coordinate of the center of the circle
y
the y coordinate of the center of the circle
r
the radius of the circle.
filled
if set to true, the circle will be filled
Description:
Draws a circle originating in (x,y) and having the r radius.
Return value:
Returns null.