replace double_epsilon by direct use of <limits>

Core/Aggregate/FTDecayFunctions.cpp

Core/Aggregate/FTDistributions1D.cpp

Core/Aggregate/FTDistributions2D.cpp

Core/Aggregate/InterferenceFunction2DParaCrystal.cpp

Core/Aggregate/InterferenceFunctionRadialParaCrystal.cpp

Core/HardParticle/FormFactorCone.cpp

Core/HardParticle/FormFactorFullSpheroid.cpp

Core/HardParticle/FormFactorHemiEllipsoid.cpp

Core/HardParticle/FormFactorTruncatedSphere.cpp

Core/HardParticle/FormFactorTruncatedSpheroid.cpp

Core/Mask/Line.cpp

Core/SoftParticle/FormFactorSphereUniformRadius.cpp

Core/Tools/MathFunctions.cpp

Core/Tools/Numeric.cpp

Core/Tools/Numeric.h