tweak file header

cpp/particles/abstract_particles_input.hpp

cpp/particles/abstract_particles_output.hpp

cpp/particles/abstract_particles_system.hpp

cpp/particles/abstract_particles_system_with_p2p.hpp

cpp/particles/alltoall_exchanger.hpp

cpp/particles/env_utils.hpp

cpp/particles/lock_free_bool_array.hpp

cpp/particles/p2p_computer.hpp

cpp/particles/p2p_computer_empty.hpp

cpp/particles/p2p_cylinder_collisions.hpp

cpp/particles/p2p_distr_mpi.hpp

cpp/particles/p2p_ghost_collisions.hpp

cpp/particles/p2p_tree.hpp

cpp/particles/particles_adams_bashforth.hpp

cpp/particles/particles_distr_mpi.hpp

cpp/particles/particles_field_computer.hpp

cpp/particles/particles_generic_interp.hpp

cpp/particles/particles_inner_computer.cpp

cpp/particles/particles_inner_computer.hpp

cpp/particles/particles_inner_computer_2nd_order.hpp