Feature: join servers based on their invite code

This removes the need to know a server IP to join it. Invite codes
are small (~7 characters) indentifiers for servers, which can be
exchanged with other players to join the servers.

src/network/core/tcp_connect.cpp

@@ -13,6 +13,7 @@
 #include "../../thread.h"
 
 #include "tcp.h"
+#include "../network_coordinator.h"
 #include "../network_internal.h"
 
 #include <deque>
@@ -48,8 +49,7 @@ TCPServerConnecter::TCPServerConnecter(const std::string &connection_string, uin
 
 		case SERVER_ADDRESS_INVITE_CODE:
 			this->status = Status::CONNECTING;
-
-			// TODO -- The next commit will add this functionality.
+			_network_coordinator_client.ConnectToServer(this->server_address.connection_string, this);
 			break;
 
 		default: