for platonic solids, use c'tor from libff

Sample/HardParticle/Dodecahedron.cpp

Sample/HardParticle/IFormFactorPolyhedron.cpp

Sample/HardParticle/IFormFactorPolyhedron.h

Sample/HardParticle/Icosahedron.cpp

Sample/HardParticle/PlatonicOctahedron.cpp

Sample/HardParticle/PlatonicTetrahedron.cpp