[Mpi-22] please review ticket #143: MPI_Request_free bad advice to users

Please review ticket #143: MPI_Request_free bad advice to users<https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/143> for MPI 2.2. I moved the original proposal (ticket #47<https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/47>) to deprecate MPI_Request_free for active requests to MPI 3.0. Thanks, .Erez *