* 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.

* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hxx,
* include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hh:
There.

* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hxx,
* include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hxx:
Use const graph_t& instead of graph_t.  The iterators now work
with bmig.

* include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/rdelta_transition_iterator.hxx:
New.  Interface and implementation.

* include/vaucanson/automata/implementation/iterators/transition_iterator_base.hxx:
Fix constness in next().
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hxx:
Add typedef to simplify type names.
Add default return value in op_weight().

Note: The iterator system compiles and DeltaTransitionIterator
can be instanciated.

* include/vaucanson/automata/implementation/iterators/transition_iterator_base.hh,
* include/vaucanson/automata/implementation/iterators/transition_iterator_base.hxx:
Have weight() return a semiring_elt_value_t instead of semiring_elt_t.
Specialize iterator_traits_.
Add typename where missing.
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hxx:
Fix iterator_traits_ to reflect changes in other files.
Add typename where missing.

* include/vaucanson/automata/implementation/iterators/transition_iterator_base.hh,
* include/vaucanson/automata/implementation/iterators/transition_iterator_base.hxx,
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hh,
* include/vaucanson/automata/implementation/iterators/delta_transition_iterator.hxx:
New.  Interface and some implementation.