copy method

@override PathEdge copy()

Make a copy, want to ensure immutability in some places

Implementation

@override
PathEdge copy() {
  return CubicEdge(
    from: from,
    to: to,
    positive: positive,
    curveSize: curveSize,
    curveAngle: curveAngle,
    bulbousness: bulbousness,
    twist: twist,
  );
}