rem: gint classement_sliste_echeance_par_date ( struct operation_echeance * a, struct operation_echeance * b )
add: gint classement_sliste_echeance_par_date ( gint scheduled_number_1, gint scheduled_number_2 )
context: gint classement_sliste_echeance_par_date ( struct operation_echeance * a, 					   struct operation_echeance * b ){    return ( g_date_compare ( a -> date,			      b -> date ));}