Make server teardown the reverse of setup

It is neater to stop announcement, deregister and close UPnP
before stopping the server so that discovering clients
can't try to connect to an already stopped server
though this is mostly just being picky because the human interaction
time scales dominate and shut down and deregister are nearly the same
time.

src/main/java/net/rptools/maptool/server/MapToolServer.java

@@ -348,21 +348,6 @@ public void stop() {
       return;
     }
 
-    server.close();
-    for (var connection : router.removeAll()) {
-      connection.removeDisconnectHandler(onConnectionDisconnected);
-      connection.close();
-    }
-
-    assetManagerMap.clear();
-
-    if (heartbeatThread != null) {
-      heartbeatThread.shutdown();
-    }
-    if (assetProducerThread != null) {
-      assetProducerThread.shutdown();
-    }
-
     if (announcer != null) {
       announcer.stop();
       announcer = null;
@@ -382,6 +367,21 @@ public void stop() {
       int port = config.getPort();
       UPnPUtil.closePort(port);
     }
+
+    server.close();
+    for (var connection : router.removeAll()) {
+      connection.removeDisconnectHandler(onConnectionDisconnected);
+      connection.close();
+    }
+
+    assetManagerMap.clear();
+
+    if (heartbeatThread != null) {
+      heartbeatThread.shutdown();
+    }
+    if (assetProducerThread != null) {
+      assetProducerThread.shutdown();
+    }
   }
 
   public void start() throws IOException {