Replace templated IntegratorReal by lambda-based RealIntegrator

Core/Aggregate/FTDistributions2D.cpp

Core/Aggregate/FTDistributions2D.h

Core/Aggregate/IPeakShape.cpp

Core/Aggregate/IPeakShape.h

Core/Aggregate/InterferenceFunction2DLattice.cpp

Core/Aggregate/InterferenceFunction2DLattice.h

Core/Aggregate/InterferenceFunction2DParaCrystal.cpp

Core/Aggregate/InterferenceFunction2DParaCrystal.h

Core/Aggregate/InterferenceFunction2DSuperLattice.cpp

Core/Aggregate/InterferenceFunction2DSuperLattice.h

Core/Aggregate/InterferenceFunctionFinite2DLattice.cpp

Core/Aggregate/InterferenceFunctionFinite2DLattice.h

Core/Aggregate/InterferenceFunctionHardDisk.cpp

Core/Aggregate/InterferenceFunctionHardDisk.h

Core/Tools/Integrator.cpp

Core/Tools/Integrator.h

Core/Tools/IntegratorReal.h

auto/Wrap/doxygen_core.i