Static code analysis: fixes for constness, level of private/protected

Core/FormFactors/src/FormFactorCrystal.cpp

Core/FormFactors/src/FormFactorWeighted.cpp

Core/Geometry/inc/BasicVector3D.h

Core/Geometry/src/Transform3D.cpp

Core/Samples/inc/HomogeneousMaterial.h

Core/Samples/inc/InterferenceFunction2DParaCrystal.h

Core/Samples/inc/Layer.h

Core/Samples/inc/LayerInterface.h

Core/Samples/inc/MultiLayer.h

Core/Samples/inc/Particle.h

Core/Samples/src/HomogeneousMaterial.cpp

Core/Samples/src/Particle.cpp

Core/Tools/inc/AxisBin.h

Core/Tools/inc/FitSuite.h

Core/Tools/inc/FitSuiteStrategy.h

Core/Tools/inc/MathFunctions.h

Core/Tools/inc/OutputData.h

Core/Tools/inc/ParameterPool.h

Core/Tools/inc/ProgramOptions.h

Core/Tools/inc/StochasticGaussian.h