This can be used from rdbg from example, to generate session files.

In particular, 'rdbg -lurette' now works thanls to this option
(cf rdbg sha 63566a893807361691137cafe15854a2a7395eec)

Remove the --generate-rdbg-load one that is less general

instead of duplicating its content

Note that from the lurette point of view, sasa plays the role of the env
as it needs to start playing, to provide Lutin the enable values for
the first demon step.

Also add the list of neighbors to the init function. The rationale is that
to give a sensible initial value to local vars of type 'Neighbor', we need
the neighbors number.

I could have chosen to pass an integer only. Well, who can the plus
can the minus.