Added small introduction to README_fr

Change-Id: Ifad62aa341ecb8bfe95b3670accc5dad2b90a189
Dico-diff: new language section template on fr.wikt
+Comments in dico-liste
Allow opening any compressed dump in all the scripts with dump_input() from basic.pm

Change-Id: I0d262c83764fd03e59e910bcee021123dbb64a65