- removed an if() block to shorten CSG tree (dunno if that helps speed)
 - added some speed tests
 - print by lines instead of polyhedron2(), because...
 - ...uniquifying edges VASTLY speeds this thing up (oh and reduces the number of objects, too)
removed spherical rod ends for speed. can add one at each vertex later
if needed?
 - geodesic now!
 - use $fn
 - specify both $fn and levels-of-bisecting from the command line