Use signal handler for checkpointing

@@ -67,0 +60,4 @@
+        Bukkit.getOnlinePlayers().forEach(player -> player.kickPlayer(null));
+
+        List<?> networkManagers = TinyProtocol.networkManagers.get(TinyProtocol.getServerConnection(Core.getInstance()));
+        if(networkManagers.isEmpty()) {

@@ -67,1 +86,4 @@
+    private static final Reflection.FieldAccessor<List> channelFutures = Reflection.getField(TinyProtocol.serverConnection, List.class, 0, ChannelFuture.class);
+    private static final Reflection.MethodInvoker bind = Reflection.getMethod(TinyProtocol.serverConnection, null, InetAddress.class, int.class);
     private static void freezeInternal(Path path) throws Exception {
+        Bukkit.getWorlds().forEach(world -> Arrays.stream(world.getLoadedChunks()).forEach(Chunk::unload));

@@ -63,2 +49,2 @@
-            }
-        }
+    public static void signalHandler() {
+        Signal.handle(new Signal("USR1"), signal -> Bukkit.getScheduler().runTask(Core.getInstance(), CheckpointUtils::freeze));