set source and destination actors for MPI messages too

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
add LGPL statements in source files

Link: http://www.gnu.org/licenses/gpl-howto.html
Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>