nodeAndConnectedEdgeDistInternal.h
==================================
Replace IO with MPIIO by a call to xExportStringDist

nodeAndConnectedEdge.h
======================
Add xxVisited methods to class nodeTo. Dirty friend functions are
not friend anymore as they now use new public API.

nodeAndConnectedEdgeDist.h
==========================
Add distributed breath first search (BFS) function with one unique
source across a distributed oriented graph. This function is template on graph
description ( but mainly use nodeTo graph API) and exchanger/functor run
has call-back to do appropriate communication/work on each node/edge
traversal. It aims to be rather generic.
From a scaling point of view performance will certainly remain poor if
the chosen source do not span on part of the graph shared by all the
processes. Next move on that topic will be to implement many source BFS
strategy that probably will covers more graph part and thus more
processes. Communication will be higher but processes will have all
something to do. And communication will be amortized (larger msg)

This new function has been successfully tested with graph created by FM.
Nevertheless a dedicated test case should be added.TODO

Xfiles_dependence.dot
=====================
Update with FM->xGraph->xTool dependency