Remove a lot of warnings (considered as errors by dune).

To do that, I have created a new dedicated module L2lExpandEnum, that
actually also deals with -eei (which was probably wrong, even if I
have not counter-exemple).

Use 1-hot encoding instead of log-encoding

I've fixed a bug in L2lExpandArrays that occurs on equation such as
  some_bool = (some_array1 = some_array2);

Also, I've rewritten Lv6Compile for more readability

Remove duplicated code when using SocMap.find and co