move multistar stuff into the src tree where it should be

networks

src/multistar/multistar.h

src/multistar/multistar_add_star.c

src/multistar/multistar_count.c

src/multistar/multistar_current_star.c

src/multistar/multistar_delete_star.c

src/multistar/multistar_limit_timestep.c

src/multistar/multistar_memsize.c

src/multistar/multistar_prototypes.h

src/multistar/multistar_rollback.c

zipup