… and ReverseContourPointPen

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.

we were alrady doing that in curveTo, so we might well do it here too

… right order

also, add test *.glif files to package_data, so users can run test modules against the installed cu2qu by doing e.g.:

```
python -m cu2qu.test.pens_test
```