On the way to add roughnesses to layers

App/App.pro

App/src/TestFresnelCoeff.cpp

App/src/main.cpp

Core/Core.pro

Core/inc/Exceptions.h

Core/inc/HomogeneousMaterial.h

Core/inc/IMaterial.h

Core/inc/ISample.h

Core/inc/Layer.h

Core/inc/LayerRoughness.h

Core/inc/MultiLayer.h

Core/src/HomogeneousMaterial.cpp

Core/src/ISample.cpp

Core/src/Layer.cpp

Core/src/LayerRoughness.cpp

Core/src/MultiLayer.cpp

Core/src/OpticalFresnel.cpp