// Transform a BezierSpiralSegment to a Bezier curve, e.g. strip it of algorithm-internal info
// and transform it from a normalized spiral to the specified center/turnSeparation.
private static Bezier ToBezier(BezierSpiralSegment src, Point center, double turnSeparation) =>
new Bezier(
p0: Transpose(src.P0.Point, center, turnSeparation),
p1: Transpose(src.P1, center, turnSeparation),
p2: Transpose(src.P2, center, turnSeparation),
p3: Transpose(src.P3.Point, center, turnSeparation));