Cleanup in Moose-Algos-Graph
- add comments
- remove useless traits
- remove duplicated code
- introduce new generic nodes: MalNodeWithNext and MalNodeWithPreviousAndNext

Add 2 alogorithms:
- Graph reducer: obtain a graph without circuits from a graph with circuits (circuits
merged in one node)
- Topological sorting: well known sort algorithm for acyclic graphes.

Thanks a lot for looking into this part of Moose.

It seems that in the meantime, the tests are red. Could you check if it is related
to this issue?

of course. It is strange, it looks like a new class was not commited.
I check that now

ok, there was an unmerged version. The latest version I published was not loaded.
I did the merge and updated the code accordingly.

There is still a problem related to the removal of the trait MalTNodeNode. I though
that I found all users of it but there is at least one remaining, preventing the loader
to load some classes.

In a previous image, MalTNodeNode users gives:
an IdentitySet(FAMIXGraphNode MalSndNode MalTraverserGraphNode MalHitsNode MalNextNode).
All these classes have been updated and do not use anymore the trait.

Thanks again. Still, the moose build is broken due to a Trait. Could you look at it?
https://ci.inria.fr/moose/job/moose-5.1/

now fixed!
I got trapped by Monticello branch mechanism. My last publication of a package was
not loaded for the CI tests.