Now all polyhedra have center of mass at origin.

Core/FormFactors/FormFactorAnisoPyramid.cpp

Core/FormFactors/FormFactorCuboctahedron.cpp

Core/FormFactors/FormFactorPolyhedron.cpp

Core/FormFactors/FormFactorPyramid.cpp

Core/FormFactors/FormFactorTruncatedCube.cpp

Core/PythonAPI/libBornAgainCore.py

Core/PythonAPI/libBornAgainCore_wrap.cxx

Tests/UnitTests/Core/S/FormFactorBasicTest.h