<_description>
The six regular 4D polytopes rotating in 4D.
Inspired by H.S.M Coxeter's book "Regular Polytopes", 3rd Edition,
Dover Publications, Inc., 1973, and Thomas Banchoff's book "Beyond the
Third Dimension: Geometry, Computer Graphics, and Higher Dimensions",
Scientific American Library, 1990.
https://en.wikipedia.org/wiki/Hypercube
https://en.wikipedia.org/wiki/Tesseract
https://en.wikipedia.org/wiki/Regular_polytope
Written by Carsten Steger; 2003.