should make sure that no sut.cmx (nor oracle.cmx) is around when
generating the lib lurette_ml_exe.cmxa.

Allow lutin files wherever lucky files were expected !!  For
instance, luc2c now accepts lutin files (so lucky do).  hum... All
those tools ougth to be renamed at some points.

Encapsulate the show_env program with a scrit sourcing set_env_var.

Makefile cleaning.