Added pay voucher feature. Added dialog with paied vouchers. Added

support for printing receipts on POS printer.

shop/shopform.h

@@ -33,6 +33,10 @@ private slots:
 
     void on_receiptCombo_currentIndexChanged(int index);
 
+    void on_payButton_clicked();
+
+    void on_showPaiedButton_clicked();
+
 private:
     Ui::ShopForm *ui;
     QSharedPointer<Voucher> m_voucher;
@@ -42,6 +46,7 @@ private:
     void doTempSave(bool comboChanged);
     void changeReceipt();
     void connectItemSignals();
+    void createEmptyVoucher();
 };
 
 #endif // SHOPFORM_H