hides particle layout operations

particle file layout is read from input by particle set, and then the
`particle_solver` object gets it from there when it needs it, so:
 - user-facing code is less verbose.
 - generic operating mode is implemented only once.

cpp/full_code/test_tracer_set.cpp

@@ -108,7 +108,6 @@ int test_tracer_set<rnumber>::do_work(void)
                 "tracers0",
                 pset.getTotalNumberOfParticles(),
                 0);
-    particles_output_writer_mpi->setParticleFileLayout(bla.getParticleFileLayout());
 
     fti->set_field(vec_field);
     trhs->setVelocity(fti);

cpp/particles/interpolation/abstract_particle_set.hpp

@@ -70,6 +70,8 @@ class abstract_particle_set
         virtual partsize_t* getParticlesPerPartition() const = 0;
         virtual const int getStateSize() const = 0;
 
+        virtual std::vector<hsize_t> getParticleFileLayout() = 0;
+
         // get p2p computer
         virtual p2p_distr_mpi<partsize_t, particle_rnumber>* getP2PComputer() = 0;
 

cpp/particles/interpolation/particle_set.hpp

@@ -329,6 +329,8 @@ class particle_set: public abstract_particle_set
                         std::swap(this->local_index[idx1], this->local_index[idx2]);
                     });
 
+            assert(this->setParticleFileLayout(particles_input.getParticleFileLayout()) == 0);
+
             return EXIT_SUCCESS;
         }
 

cpp/particles/particle_solver.cpp

@@ -77,6 +77,7 @@ int particle_solver::writeCheckpoint(
 {
     TIMEZONE("particle_solver::writeCheckpoint");
     particles_output_writer->update_particle_species_name(this->particle_species_name);
+    particles_output_writer->setParticleFileLayout(pset->getParticleFileLayout());
     particles_output_writer->template save<state_size>(
             this->pset->getParticleState(),
             this->additional_states.data(),