Input and output rings have opposite winding

[e-n-f]

https://github.com/mapbox/wagyu/blob/ring-orientation/tests/orient.cpp contains a simple example of asking wagyu to process a single ring. The input ring is

(0,0), (1,0), (1,1), (0,1), (0,0)

and the output is

(1,0), (0,0), (0,1), (1,1), (1,0)

If it isn't clear, the problem is that the points are in the opposite order in the input and the output. (They also start counting from a different point around the ring, but that is fine and expected.)

cc @flippmoke