revert insertion of iSlice in ParticleInSlice

Resample/Processed/ProcessedLayout.cpp

@@ -143,7 +143,6 @@ ProcessedLayout::processParticle(const IParticle& particle, const SliceStack& sl
                 limits = {slice.zBottom() - z1, slice.zTop() - z1};
             }
             ParticleInSlice pis = particle->createParticleInSlice(limits);
-            pis.iSlice = iSlice;
 
             const Material& material = slices.at(iSlice).material();
             const std::unique_ptr<IFormFactor> ff(pis.sliced_ff->clone());

Sample/Particle/Particle.cpp

@@ -63,5 +63,5 @@ ParticleInSlice Particle::createParticleInSlice(const ZLimits& limits) const
     Material transformed_material(
         m_rotation ? m_material.rotatedMaterial(m_rotation->getRotMatrix()) : m_material);
     sliced_ff->setMaterial(transformed_material);
-    return {0, std::move(sliced_ff), {{{volume, transformed_material}}}};
+    return {std::move(sliced_ff), {{{volume, transformed_material}}}};
 }

Sample/Particle/ParticleInSlice.h

@@ -31,7 +31,6 @@
 //! @ingroup intern
 
 struct ParticleInSlice {
-    size_t iSlice {0};
     std::unique_ptr<IFormFactor> sliced_ff;
     Admixtures admixtures;
 };