This work is the remix of the original voronoi_sphere module created by Bob Marchese and OpenSCAD Voronoi algorithm by Felipe Sanches.
voronoi3d module is moved to the separate file and optimized (no more decorative Minkowski operation, better nuclei distribution, etc.). However rendering is still very slow because of O(n^2) complexity of the algorithm.
Sufficient support threshold is 40% (which default in Sli3r).
Do not place real fire candles under the lampshade -- danger of fire! Use battery-powered candles instead.