A lot of fix on point of sale module

htdocs/admin/cashdesk.php

htdocs/cashdesk/include/environnement.php

htdocs/cashdesk/templates/menu.tpl.php

htdocs/cashdesk/validation_verif.php

htdocs/compta/paiement.php

htdocs/includes/modules/modCashDesk.class.php

htdocs/langs/en_US/admin.lang

htdocs/langs/fr_FR/admin.lang

htdocs/lib/functions.lib.php