* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hh,
include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hh,
include/vaucanson/automata/implementation/iterators/transition_iterator_base.hh
(iterator_traits_): Do not inherit from a base class, as it does not
fit well with our static inheritance idiom.