expanser to expand the mentioned node.

instead of silently generate  (syntactically) wrong lustre v4 (or ec).

The rationale for this change is that this is necessary for constants
appearing static  arg to  be replaced. One  problem is that  they are
handled in exactly  the same way as top-level  constants, which could
be left  un-expanded. I could make  something in order  to not expand
those top-levelconstants, but is it worth the trouble ?

To do that,  I have changed sligthly the  representation of Eff.ARRAY
(the elements  are now  attached to the  constructor itself,  and the
operands  is empty)  and  the one  of  array constant  (we attach  to
Array_const_eff  a  list  instead  of  an  array,  for  the  sake  of
homogeneity) with what is done in Eff.val_eff.

change the parser and accept only clock expressions after a when.

A clock is now made of 2 idents: one for the clock constructor, and
one for the clock variable.

to avoid name clashes in the lic.

SolveIdent.recognize_predef_op  that  replaces  node call  by  Predef
constructor  when   necessary,  via  a  complete   traversal  of  the
SyntaxTree (instead  of doing it  in the parser). The  rationales for
this change are that:

- it is quite tedious to do it in parser as multiple locations are involved
- I did missed some locations
- It makes the parser more focused on parsing issues
- that traversal  is a first step  do deal with  idref solving (hence
 the name of the new module that contains that function

Note that lsrc/test/should_work/fab_test/lecteur.lus was using
"plus" as a variable ident, which raised an error, which

Also, node aliased to other nodes were handled poorly: I was replacing
in the syntax tree the node by its alias. Now, I really define
the alias node using the aliases one.

For instance,

    node toto(x:t) returns (y:t);
    let
      ...
     tel
     node titi = toto;
     node tutu(...) returns(...);
     let
        ...
	z = titi(a);
     tel

was compiled into

    node toto(x:t) returns (y:t);
    let
      ...
     tel

     node tutu(...) returns(...);
     let
        ...
	z = toto(a);
     tel

Now, I generate

     node toto(x:t) returns (y:t);
     let
       ...
     tel
     node titi(i1:t) returns (o1:t);
     let
       o1 =toto(i1);
     tel
     node tutu(...) returns(...);
     let
        ...
	z = titi(a);
     tel

which is equivalent, but closer to the original program.

not compile them is (well, was) the default...).

also, during pretty-printing, remove the type in the constant definition
(e.g., "const x = 42;" instead of "const x = 42:int;"), except if it is an abstract
constant of course

For non-regression tests, do not use Lazycompiler.test function
anymore and just use  LazyCompiler.node_check instead.

put in the new file compiledDataDump.ml all the stuff
related to string convertions of CompiledData items.

	Try to split this 400 lines (!) function.
	+ Factorize some duplicated code.

Ident.t is now an abstract data type (instead of a string).
fullid is turned into an Ident.long, and is also made abstract.