nb: does not really work yet.

Update: add the previous state in argument of the fault function.

New: add a fault functions to the Algo (to inject fault when a legitimate configuratiuon is reached).

nb: I needed to  split Main to avoid a Module self-loop  (as I need to
use do_step in Daemon).

To force that, I've changed the Register interface (and thus GenRegister)

The rationale is that:
- in lurette mode, they should be the same for all algos already
- in batch mode, action declarations are ignored anyway (except in custom mode)

Its basename is the basename of the name of the .dot file.

Also provide a =--gen-register= option generates such a registring ml
file. --gen-register also generate a state.ml skeleton file.

The Makefile test/Makefile.inc also suppose that the types of the state
is defined in state.ml