Added recalculating receipt on item count changed. Some UI changes.

shop/shopservice.cpp

@@ -29,9 +29,14 @@ void ShopService::calculate(QSharedPointer<Voucher> voucher)
     QDecDouble total;
 
     foreach (QSharedPointer<VoucherItem> item, voucher->items()) {
-        QDecDouble itemPrice = item->unitPrice() * item->count();
-        total += itemPrice;
+        calculateItem(item);
+        total += item->price();
     }
 
     voucher->setTotalPrice(total);
 }
+
+void ShopService::calculateItem(QSharedPointer<VoucherItem> item)
+{
+    item->setPrice(item->unitPrice() * item->count());
+}