t, and a node returning such a t, the compiler was actually returning
the type definition of t (instead of the abstract type).

In  order  to fix  that,  it  was necessary  to  add  in argument  of
Lazycompiler.solve_x_idref  a  flag  (named provide_flag)  indicating
whether the  item being  compiled appears in  the provide, or  in the
body part of the package.

This fix  triggered another bug that  we also fix: indeed,  it is not
correct to return  a compile error when the  provided parameters of a
node is not equal to  its implementation. Indeed, such parameters can
be abstract type that are defined in that package.

The test "should_work/packEnvTest/packages.lus" is now ok.

	type 'a hereflagged =
	  Here of 'a
	| NotHere of Ident.long
into
	type 'a elt =
	  Local of 'a
	| Imported of Ident.long * static_arg list

i.e., i am basically doing two things:
 - fix poor naming
 - adding static arg to nodes

indeed, when compiling an equation that involves nodes defined
in another package, I need to check that the static args and the
static params match. Therefore I need to have the static params !
Therefore I add them (I will use them in the next commit).

Moreover, in SyntaxTreeCore.node_info, the static_params list was
an option type, which is a bit weird (empty lists are enough to
represent node with no static params).

and anonymous structures. I've even found some type errors in the non-reg files!

Add Some lustre files that are automatically tested thanks to the
generic Makefile (from the Youssef compiler).

Test files are organized as follows :

 - files in directories that are under the "should_fail" directory
  do triggers errors, but it is intented

	should_fail/syntax
	should_fail/type
	should_fail/semantics

 - and files that should not trigger any error:

	should_work/