Add shutdown of bau after one minute no player

BauSystem_Main/src/de/steamwar/bausystem/BauSystem.java

@@ -165,6 +165,9 @@ public class BauSystem extends JavaPlugin implements Listener {
         Player p = e.getPlayer();
         SWScoreboard.removeScoreboard(p);
         if (Bukkit.getOnlinePlayers().isEmpty() || (Bukkit.getOnlinePlayers().size() == 1 && Bukkit.getOnlinePlayers().contains(p))) {
+            if (autoShutdown != null) {
+                autoShutdown.cancel();
+            }
             autoShutdown = Bukkit.getScheduler().runTaskLater(this, Bukkit::shutdown, 1200);
         }
     }