mv RoughnessModel to LayerRoughness

Resample/Processed/ReSample.cpp

Resample/Slice/SliceStack.h

Resample/Specular/ComputeFluxMagnetic.cpp

Resample/Specular/ComputeFluxScalar.cpp

Sample/Interface/LayerRoughness.h

Sample/Multilayer/MultiLayer.cpp

Sample/Multilayer/MultiLayer.h

Sample/StandardSample/FeNiBilayerBuilder.cpp

Sample/StandardSample/MagneticLayersBuilder.cpp

Sample/StandardSample/MultiLayerWithNCRoughnessBuilder.cpp

auto/Wrap/libBornAgainSample.py

auto/Wrap/libBornAgainSample_wrap.cpp