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/