Interface that describes a Path object which is defined by control points. In practice this only means Bézier curves, both quadratic (one control point) and cubic (two control points). This interface is relevant in the context of Smooth (Shorthand) Bézier curves, which omit a control point from their arguments list because it can be calculated from the last control point of the previous curve. Therefore, the last control point of a curve must be exposed to the PathSvgNodeRenderer algorithm.