Fix socket initialization in TcpService.
Polish service_status_box.glade.
Add TcpService::get_port().
Add MulticastService::get port() and change type of Multicast::multicast_address variable.
Implement MainWindow::update_service_status() methods.
Initialize TcpService and set initial service status (in main window) in Service.
Introduce Connection class stub.
Update Protocol::MessageType enumeration.