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

Indeed it is possible when each branch of the ite updates no memory.
This is done in the new L2lOptimIte module.

For the time being, it does detect when the node has no memory. It
only looks at the declaration: nodes have memory, and not functions.

I should infer that information and raise warnings or errors if what
I infer is not compatible with waht is declared (will come later).

Also split ActionsDep into ActionsDep and Action.

Also fix a bug in L2lsplit where deeply nested (>2) merge were not
splitted.

nb: les tests ne passent toujours bien sur.

* Partie lus -> AST

predef.ml -> srcPredef.ml
syntaxTreeCore.ml -> astCore.ml
syntaxTree.ml     -> astV6.ml
syntaxTreeDump.mli-> astV6Dump.mli

* Partie Ast -> Ast

solveIdent.mli -> astRecognizePredef.mli
syntaxTab.mli -> astTab.mli
symbolTab.mli -> astTabSymbol.mli

* Partie  AST -> lic (static evaluation)

eff.ml  -> lic.ml
getEff.mli -> ast2lic.mli
lazyCompiler.mli -> licTab.mli
builtIn.ml -> licMetaOp.ml
predefEval*.ml -> licEval*.ml
name.mli -> licName.mli

* Partie Lic -> Lic

uniqueOutput.mli      -> l2lCheckOutputs.mli
structArrayExpand.mli -> l2lExpandArrays.mli
nodesExpand.mli       -> l2lExpandNodes.mli
doNoPoly.ml           -> l2lRmPoly.ml
doAliasTypes.ml       -> l2lAliasType.ml
doSplit.ml            -> l2lSplit.ml