alternative elsif branch not tested

[Mehdi Saada <00120260a@gmail.com>]

This piece shall verify the program's arguments. I don't understand why whatever the first argument is, it doesn't raise EXC_COMMANDE as expected.
It should do it if ARGUMENT(1)(1) isn't 'n','c','N','C'.
Except that, everything worked just fine. Almost at the first attempt !

      if Argument_Count /= 2 then PUT_LINE ("Pas le bon nombre d'arguments."); raise Exc_Commande;
      elsif Argument (1)'Length /= 1 and ARGUMENT(1)(1) not in 'n'| 'c'| 'N' | 'C' then
	 PUT_LINE ("Première argument incorrect: veuillez mettre un (seul) charactère entre n, c, N et C."); raise Exc_Commande;
      elsif ADA.Strings.Fixed.Index (Argument (2), Alphanumeric_Set, Outside) /= 0 then
	 PUT_LINE ("Deuxième argument incorrect: l'acronyme ne peut pas contenir de chiffres !"); raise Exc_Commande;
      end if;