This was needed for when we were supporting the old robofab.ufoLib
where anchors were represented as single-point-with-a-name contours.
With latest ufoLib, even when glif format is 1, anchors are
stored separately and are not drawn with pens (only proper contours
and components are passed on in the draw method).
So there is no longer need to special-case single points.
It's not the job of the cu2qu pens to filter those out.
This is still the same contour as before, as UFO spec allows both;
it's just normalized so that the first segments' off-curves appear at
the bottom, and the first point in the contour is an on-curve.
I copied the ReverseContourPointPen from the robofab.pens. I think it's useful for the Cu2QuPen to
have a `reverse_direction` argument which inverts the contours' winding direction. I didn't want to
add a dependency on robofab, since things are in transitions... We will add it to the future "penBox"
package (or whatever it'll be called) once that is set up.
