(scm_c_vector_set_x): Make return type

(scm_c_vector_set_x): Make return type
void.
(scm_is_vector, scm_vector_p, scm_vector_length,
scm_c_vector_length, scm_vector_ref, scm_c_vector_ref,
scm_vector_set_x, scm_c_vector_set_x, scm_vector_to_list,
scm_vector_move_left_x, scm_vector_move_right_x,
scm_vector_fill_x): handle one-dimensional arrays.
(scm_vector_elements, scm_vector_release_elements,
scm_vector_frame_release_elements, scm_vector_writable_elements,
scm_vector_release_writable_elements,
scm_vector_frame_release_writable_elements): New.
(scm_list_to_vector, scm_vector_to_list, scm_vector_fill,
scm_vector_move_left_x, scm_vector_move_right_x): Use them.