New: don't stop when no process is enabled

lib/sasacore/demon.ml

-(* Time-stamp: <modified the 28/03/2019 (at 18:01) by Erwan Jahier> *)
+(* Time-stamp: <modified the 28/03/2019 (at 20:56) by Erwan Jahier> *)
 
 type t =
   | Synchronous (* select all actions *) 
@@ -19,7 +19,7 @@ let (random1: 'a list list -> 'a list) =
 
 let rec (random: 'a list list -> 'a list) =
   fun all ->
-    assert (all <> []);
+    (*     assert (all <> []); *)
     let al = List.map random_list all in
     let al = List.filter (fun _ -> Random.bool ()) al in
     if al = [] then random all else al