some fixes

PIEthernet::listen
PIClientServer::Server::~Server
PISystemTime const sleep
ClientServer tests fast and stable

libs/main/io_devices/piethernet.cpp

@@ -527,6 +527,7 @@ bool PIEthernet::listen(bool threaded) {
 		listen_threaded = true;
 		server_bounded  = false;
 		server_thread_.start(server_func);
+		server_thread_.waitForStart();
 		return true;
 	}
 	listen_threaded = server_bounded = false;