[BUGFIX] Limit tax classes to current order

Currently all tax classes from all orders are loaded instead of the
specifc ones from current oder item only. This breaks expansion of
TYPO3 IRRE element if you have a lot of orders.

Author: andreashager

Configuration/TCA/tx_cart_domain_model_order_product.php

@@ -154,6 +154,7 @@
                 'renderType' => 'selectSingle',
                 'readOnly' => 1,
                 'foreign_table' => 'tx_cart_domain_model_order_taxclass',
+                'foreign_table_where' => 'AND {#tx_cart_domain_model_order_taxclass}.{#item} = ###REC_FIELD_item###',
                 'minitems' => 1,
                 'maxitems' => 1,
                 'appearance' => [