lustresf: Better construction of lustre ast. Still more work to be done.

src/modules.ml

src/tools/stateflow/models/model_simple.ml

src/tools/stateflow/models/model_stopwatch.ml

src/tools/stateflow/semantics/cPS.ml

src/tools/stateflow/semantics/cPS_ccode_generator.ml

src/tools/stateflow/semantics/cPS_lustre_generator.ml

src/tools/stateflow/semantics/cPS_transformer.ml

src/tools/stateflow/sf_sem.ml