Added fbyn(expr, n, init) to encode 
init -> pre (init -> pre (init -> ... pre expr))
with n occurences of init

 - corrected a regression bug in main_lustre_compiler.ml (optional generation of lusic files was in a bad ocaml pattern-matching rule...)
 - added a flush in Log to help find out the exact phase when the compiler crashes or stops silently 

 - destination dir should now work properly
 - lusic files now have a version number, to avoid nasty segfaults
   when loading lusic files created by an older compiler version
 - inlining should now work with generic nodes and generic array library
 - tests_ok_dev.list has been added that focuses on advanced (but unused !)
   features of lustrec, avoiding the large 'kind' test files 

 - global constants were not accounted for
 - no good avoidance of name capture when inlining
 - static parameters (array sizes and clocks) not handled
 - ill-typed generated expressions, when inlining array expressions

 - a small problem in the parser
 - regarding the handling of destination directory, source directory, current directory, etc.
   It seems to be working now. A nice chasing after weird behaviors...