Clear note messages to avoid trailing letters

src/main.rs

@@ -299,6 +299,7 @@ fn main() {
             None => ()
         }
         while let Ok((ts, msg)) = rx.try_recv() {
+            window.mvprintw(5, 0, "                                        ");
             window.mvprintw(5, 0, format!("{:?} {}.{:03}", msg, ts/1000, ts%1000));
         }