RTDEClient: pause and stop in destructor only if running

Otherwise we produce an error when destructing an initialized, but
non-started client.

Author: urfeex

src/rtde/rtde_client.cpp

@@ -445,10 +445,13 @@ void RTDEClient::setupInputs()
 void RTDEClient::disconnect()
 {
   // If communication is started it should be paused before disconnecting
-  if (client_state_ > ClientState::UNINITIALIZED)
+  if (client_state_ == ClientState::RUNNING)
   {
     sendPause();
     pipeline_->stop();
+  }
+  if (client_state_ > ClientState::UNINITIALIZED)
+  {
     stream_.disconnect();
   }
   client_state_ = ClientState::UNINITIALIZED;