send heartbeat while waiting for control to finish

remote_control/measurement_server.py

@@ -76,7 +76,8 @@ class MeasurementHandler(socketserver.BaseRequestHandler):
             # TODO this assumes that we wait only for at most one response at a time
             #      we could add some kind of reference here to handle multiple responses (e.g. id of the response to wait for)
             while self.server.response_queue.empty():
-                time.sleep(0.1)
+                time.sleep(0.2)
+                self.request.sendall(b'.\n')
                 pass
             reply = self.server.response_queue.get()