Disconnect client by throwing exception in handler

This makes it easier to add checks in handlers, which should improve security over time.
I think this approach is more readable and testable than calling Client#disconnect straight up,
while it also decentralizes the handling.

src/main/java/net/netty/LoginServerInitializer.java

@@ -1,6 +1,7 @@
 package net.netty;
 
 import client.Client;
+import database.character.CharacterSaver;
 import io.netty.channel.socket.SocketChannel;
 import net.PacketProcessor;
 import net.server.coordinator.session.SessionCoordinator;
@@ -10,6 +11,10 @@ import org.slf4j.LoggerFactory;
 public class LoginServerInitializer extends ServerChannelInitializer {
     private static final Logger log = LoggerFactory.getLogger(LoginServerInitializer.class);
 
+    public LoginServerInitializer(CharacterSaver characterSaver) {
+        super(characterSaver);
+    }
+
     @Override
     public void initChannel(SocketChannel socketChannel) {
         final String clientIp = socketChannel.remoteAddress().getHostString();