exec_spanZ hides overloads from public spanZ

Examples/scatter2d/CustomFormFactor.py

Sample/HardParticle/IFormFactorPolyhedron.cpp

Sample/HardParticle/IFormFactorPolyhedron.h

Sample/HardParticle/IFormFactorPrism.cpp

Sample/HardParticle/IFormFactorPrism.h

Sample/HardParticle/Sphere.cpp

Sample/HardParticle/Sphere.h

Sample/Particle/IFormFactor.cpp

Sample/Particle/IFormFactor.h

auto/Wrap/libBornAgainSample.py

auto/Wrap/libBornAgainSample_wrap.cpp

auto/Wrap/libBornAgainSample_wrap.h