i <radius> <angle> <anticlockwise>

  = circular arc with the given radius, beginning in the current bearing
    direction, drawing <angle> degrees of the circle, defaults to going clockwise

e <radius-x> <radius-y> <start-angle> <end-angle> <anticlockwise>

  = elliptical arc with the given radii, beginning in the current bearing direction,
    as if you were <start-angle> already around the ellipse, going to <end-angle>,
    defaults to going clockwise