TEST: try to track currentCashState

... but this is currently useless because we can not detect overpayment
here.

src/ATBAPP/ATBDeviceControllerPlugin.h

@@ -127,6 +127,8 @@ private:
 
    quint8 currentSelectedTicketType;
 
+   nsDeviceControllerInterface::CASH_STATE currentCashState;
+
 private slots:
    // printer