New: Add clone feature on invoices.

htdocs/admin/facture.php

htdocs/comm/mailing/fiche.php

htdocs/comm/mailing/mailing.class.php

htdocs/compta/commande/pre.inc.php

htdocs/compta/facture.php

htdocs/compta/pre.inc.php

htdocs/facture.class.php

htdocs/html.form.class.php

htdocs/html.formmail.class.php

htdocs/includes/menus/barre_left/eldy_backoffice.php

htdocs/includes/menus/barre_left/eldy_frontoffice.php

htdocs/includes/menus/init_menu_auguria.sql

htdocs/includes/modules/facture/pdf_crabe.modules.php

htdocs/includes/modules/facture/pdf_huitre.modules.php

htdocs/langs/en_US/bills.lang

htdocs/langs/en_US/other.lang

htdocs/langs/fr_FR/bills.lang

htdocs/langs/fr_FR/other.lang