This new container in the family of Send And Receive operation will
provide a specific from/to selection of the key. This give a way to
communicate in a ring manner for example.
The key are still accumulate with a key manager. But from/to (given at
construction time) will place it in send or receive map or ignore it
depending if current proc id correspond respectively to "from" or
"to" or none of them.
This mechanism may be viewed as a sophisticate send mechanism:
* It deal with key/information concept to store info to send. This is
rather more sophisticate than the simple send as key order may be used to
reduce information volume to be send.
* It use asynchronous mechanism
* It encapsulate all MPI in exchangeInformation and associated object