Fight against key tva_taux. Removed completely.

htdocs/core/class/html.form.class.php

...s/core/modules/expensereport/doc/pdf_standard.modules.php

htdocs/expensereport/card.php

htdocs/expensereport/class/expensereport.class.php

htdocs/install/mysql/tables/llx_expensereport_det.sql

htdocs/product/class/html.formproduct.class.php