message: qt: Use parent-child relation to manage lifetime of OptionsModel object
  Both BitcoinApplication and OptionsModel classes are derived from the
  QObject class, therefore a parent-child relation could be established to
  manage the lifetime of an OptionsModel object.
  This commit does not change behavior.
diff: @@ -212,8 +212,6 @@ BitcoinApplication::~BitcoinApplication()
  delete window;
  window = nullptr;
  - delete optionsModel;
  - optionsModel = nullptr;
  delete platformStyle;
  platformStyle = nullptr;
  }
  @@ -227,7 +225,7 @@ void BitcoinApplication::createPaymentServer()
  void BitcoinApplication::createOptionsModel(bool resetSettings)
  {
  - optionsModel = new OptionsModel(m_node, nullptr, resetSettings);
  + optionsModel = new OptionsModel(m_node, this, resetSettings);
  }
  void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
  