To do that, we :

(1) totally remove  (in the  ocaml code) the  use of "oper",  and use
"node" instead.  Indeed, a node  is a memoryfull operator, as opposed
to function that are memoryless operators.  However, lus2lic does not
really care about memoryless  and memoryfull information. Therefore I
prefer  to use  node everywhere,  and to  flag node_info  to indicate
whether it has memories or not.

(2) change the syntaxTreeCore type to make it more general. Indeed,
    the distinction between functions and nodes was

    - redundant:  extern nodes  and (extern)  functions  were handled
    differently (NodeExtern versus ExtNode (was named FUNC before)).

    - and  incomplete:   it  was  not  possible   to  provide  static
      parameters to function, nor to define functions with body, etc.

Now a  function is  just a memoryless  node. The check  that function
indeed use no memory will be done later.

(3) also,  change  the  parser   so  that  functions  with  body  are
    accepted.

(4) in order  to do it step by  step, I add the  "extern" keyword" so
    that extern nodes and functions are more easy to parse. I will
    remove it later.

	Do not test nodes with static params as it is too difficult
  	to do from the top-level automatically. Indeed, it would
	require to build effective static arg before, which would
	require to make node_check mutually recursive with type_check
	and co. Its not worth the trouble, as such node can be tested
	anyway if used.

LazyCompiler.solve_node_idref:
	compile (with the new function check_static_arg) static
	params instead of ignoring them.

EvalConst.eval_const -> EvalConst.f
	for simplicity and homogeneity with the naming scheme used in EvalType.

Better error msgs.

Renaming idents.

	 oper -> node
	 func -> extern node
	 node -> (user) node

	 CALL_BY_NAME -> STRUCT_n
	 STRUCT_EXP_n -> STRUCT_anonymous_n
	 flaged -> flagged

src/syntaxTreeCore.ml (new file)
	Split      syntaxTree.ml      into     syntaxTree.ml      and
	syntaxTreeCore.ml. The idea is that lic2loc should be able to
	use syntaxTreeCore.ml verbatim.

src/lxm.ml
src/lxm.mli
	remove pack_name from  this module, so that it  can be shared
	with  lic2loc too  (this is  mandatory  since it  is used  by
	SyntaxTreeCore)

src/compile.ml
src/compiledData.ml
src/evalConst.ml
src/evalConst.mli
src/evalType.ml
src/evalType.mli
src/expandPack.ml
src/lazyCompiler.ml
src/main.ml
src/parser.mly
src/symbolTab.ml
src/symbolTab.mli
src/syntaxTab.ml
src/syntaxTreeDump.ml
src/syntaxTreeDump.mli
src/test/Makefile
src/test/packs.lus
src/test/test.res.exp
	opening SyntaxTreeCore  module, and inline  the definition of
	Lxm.pack_name.

	Also,  begin  to  replace  oper  by node  or  predef_node  in
	identifiers, in order to get a more consistant naming scheme.

src/lxm.ml:
src/global: (new file)
   Add the lustre file name in error messages.

src/compiledData.ml:
   Better Data structure dumping (string_of_type_eff,string_of_const_eff),
   and more dumping (LazyCompiler.check_const_interface).

src/lazyCompiler.ml:
   Fix a bug that prevented enum constants to be exported.
   Indeed, in LazyCompiler.const_check_interface_do, only extern
   constants (Extern_const_eff) were accepted in the provided part, whereas
   enum contants (Enum_const_eff) should also be accepted.

   Force constants interface checking in LazyCompiler.test.

src/test/Makefile:
src/test/onlyroll.lus:
src/test/heater_control.lus:
src/test/pfs.lus:
   Some more test files.

ParserUtils.flat_flaged_list -> ParserUtils.flat_flagged_list

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