This is particularly useful when used with sasa, to be able to debug
self-stabilizing algorithms.

This change also fix the use of  'rdbg -lurette' with sasa.

It also make  rdbg-batch useless.  Indeed, the rdbg  -lurette mode was
generating a  luretteSession.cmxs file to  be used by  rdbg-batch. Now
rdbg generates  a standalone  luretteSession binary, which  solves the
double stage of Dynlinking issue.