message: add message box if no terminal was found
diff: @@ -2680,8 +2680,14 @@ void RepoView::openTerminal()
  #endif
  }
  - if (terminalCmd.isEmpty())
  + if (terminalCmd.isEmpty()) {
  + auto messagebox = QMessageBox(this);
  + messagebox.setWindowTitle(tr("No terminal executable found"));
  + messagebox.setText(tr("No terminal executable was found. Please configure a terminal in the configuration."));
  + messagebox.setStandardButtons(QMessageBox::Ok);
  + messagebox.exec();
  return;
  + }
  #if defined(Q_OS_WIN)
  // No direct method of QProcess can take a raw command line and a working directory
  