Fix wakes!

[rattle]

Not much of a feature but a bugfix request.

Wakes require two vertices to function properly. They are being shot in the direction of these two vertices. What I'd like to see is the object rotation getting used instead when there is no geometry (so OTA ships will continue to work).

At the moment they are being emitted in the direction of the object but are getting shot in the direction of the first two vertices.

Also, upspring crashes for me when trying to import objects with less than three vertices..