[lustrev] fixed some issues when calling Z3. Seems working for the moment: basic call to Z3 and sat/unsat result

- arrow.ml* to define basic builder for arrow (node, name, ...)
- machine_code_common similar to corelang but for machine_code (printers, some builders, ...)
- machine_code restricted to the translatation from normalized nodes to machines

Structs defining machines are now in machine_code_types

- Renamed type declarations as lustre_types and machine_code_types