Remove a lot of warnings (considered as errors by dune).

cf rdbg git 66d01f567940e06eab9a49604663d43c29fdfe01

(cf 55d3d77c470f416befd16a1b7d47f751eb2171fc)

Fix a bug in socExec.ml (strangely untriggered before) along the way.

Some work to share the conde that is comon to Lutin/Lurette more properly
via Makefiles and using chmod to avoid editing the wrong files.

+ mv the lus2licRun.ml/mli file to the Lurette git repo.

Also Merge the Global and the MainArg module as they were
(bizzarely) both handling command args options.