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

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.

node_Table hashtbl is now only available through functions of the corelang.mli

- a bug in regressio ntest Simulink/integrator_ext_IC_matrix_test revealed the following (serious issue):
  when building the list of instruction (in the machine code) the access to variable were hardcoded to LocalVar or StateVAr depending whether the variables was part of the identified memories.
  Un fortunately the set of memories is only known after iterating through all definitions. A read access to a memory which was scheduled before its update was generating a non compilable C code:
  the access to the memory x which should be written as mem->x was written as a local access "x". But x was not declared as a local variable: hence gcc compile error.

  The current commit is pretty involved. It goes through all the code:
  - LocalVar and StateVar have been merged in Var in machine instructions (rhs ie expressions)
  - any possible print or access to these shall be given access to the machine (ie its memories)
    so a lot of functions have been enriched with a machine first argument.

  Regression tests performed well showing no additional bug introduced.  The only Unstable->Broken changes are the DIFF which could not be run at all before.

SEAL: compute the projection to switched systems. Some issues with intermediate variables and a better selection of split guard have to be addressed

- 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

Adapted the parser/types/constructors for cocospec syntax

- Renamed type declarations as lustre_types and machine_code_types

- program type renamed as program_t
- Initiating the lustrev tool with dependencies to z3 and seal.

[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

[global] reordered local vars, keeping the declared ones before the others. Was mandatory for clocked expressions in compiled automata.

This is used in EMF backend.

nice bug correction wrt constants with a large number of digits. Would raise exception when comparing these constants