ast modifs and additional arrow_taint phase to retrieve which arrow "protects" / "taints" which variable

- Bugs in partial evaluation for equalities among bool constants
  and a nice recursive call generating a stack overflow! Now solved
- Setup a timeout for z3 in seal
- Better log for seal

Array access: solved issues in C backend when basic operations in array access dimensions. Also better handling in EMF, ie further normalization through new equations

Contract resolution still need to be done as well as dealing with the machine code level and so on.

Different parsers yet but shared process.
In case of lusi input the C backend is bypassed since the .h is generated from the lusic and no C code should be generated since it may overwrite existing manually written code

But

- Modules now is more integrated and performed the building of the type/clock env.
  previously some computation were performed twice by different functions. Some of these functions have been moved from compiler_common to modules

- Adapted the parsing of specification with a cocospec compatible one
- The data structure of contracts is now almost cocospec compatible
- Lustrec-test has been updated to use the newest syntax

- Renamed type declarations as lustre_types and machine_code_types

[general] large modification: added machine types, a second typing phase dealing with machine types (eg uint8)
          typing was transformed as a functor and parametrized by basic types (int/real/bool)
          it can also be applied multiple times on the same program

- EMF backend now impose the optimization level to be set to 0 in order to avoid equation elimination that would render traceability difficult
- Options.ml has been split into Options.ml / Options_management.ml. Options.ml only contains references and no functions

[bug] seems to crash with EMF backend

- allow multiple -I dir, will be used in order (first one declared
  is first used)

- when declaring a global library #open <foo>, foo is first checked
  in local folders, than in global one (install path). This
  does not apply to local libraries opened with #open "foo".

functional: keep it as is
non func: introduce a fresh local var v and replace assert(e) by v=e; assert (v);

 - bizarre date stamping (when generating .lusi files)
 - bug in loading libraries, forbidding several (transitive) imports of the same library.
 - plugin scopes was wrongly always activated