Analytic PolyhedronGeometry

Remove recursive calls from PolyhedronGeometry, replacing them with an
analytical construction of the geometry.

In unscientific studies, at high detail levels (> 5), this appears to yield
a ~30% reduction in runtime.
Copy face normal.
Merge remote-tracking branch 'bhickey/dev' into dev
Using IcosahedronGeometry in LOD example.
PolyhedronGeometry code clean up.
Updated builds.