Merge remote-tracking branch 'upstream/develop' into develop

.appveyor.yml

Core/Computation/MainComputation.cpp

Core/Computation/MainComputation.h

Core/Computation/RoughMultiLayerComputation.cpp

Core/Computation/RoughMultiLayerComputation.h

Core/DecoratedFormFactor/FormFactorDecoratorMaterial.cpp

Core/DecoratedFormFactor/FormFactorDecoratorMaterial.h

Core/Export/ExportToPython.cpp

Core/HardParticle/FormFactorPolyhedron.cpp

Core/Instrument/Beam.cpp

Core/Instrument/Beam.h

Core/Instrument/DetectionProperties.cpp

Core/Instrument/DetectionProperties.h

Core/Instrument/IDetector2D.cpp

Core/Instrument/IDetector2D.h

Core/Material/HomogeneousMaterial.cpp

Core/Material/HomogeneousMaterial.h

Core/Multilayer/Layer.cpp

Core/Multilayer/Layer.h

Core/Multilayer/SpecularMagnetic.cpp