Debug multicurrency and clean properties of some modules

htdocs/admin/multicurrency.php

htdocs/comm/propal.php

htdocs/commande/card.php

htdocs/compta/facture.php

htdocs/contrat/card.php

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

htdocs/core/modules/modCategorie.class.php

htdocs/core/modules/modDocumentGeneration.class.php

htdocs/core/modules/modExport.class.php

htdocs/core/modules/modFckeditor.class.php

htdocs/core/modules/modImport.class.php

htdocs/core/modules/modLabel.class.php

htdocs/core/modules/modMultiCurrency.class.php

htdocs/core/modules/modWebsites.class.php

htdocs/fourn/commande/card.php

htdocs/fourn/facture/card.php

htdocs/install/mysql/migration/3.9.0-4.0.0.sql

htdocs/install/mysql/tables/llx_multicurrency_rate.sql

htdocs/langs/en_US/admin.lang

htdocs/langs/en_US/receiptprinter.lang