Fix several problems on new REST API on project/tasks

htdocs/adherents/class/api_members.class.php

htdocs/adherents/class/api_subscriptions.class.php

htdocs/api/class/api.class.php

htdocs/api/index.php

htdocs/categories/class/api_categories.class.php

htdocs/categories/class/api_deprecated_category.class.php

htdocs/comm/action/class/api_agendaevents.class.php

htdocs/comm/propal/class/api_proposals.class.php

htdocs/commande/class/api_deprecated_commande.class.php

htdocs/commande/class/api_orders.class.php

htdocs/compta/bank/class/api_bankaccounts.class.php

htdocs/compta/facture/class/api_deprecated_invoice.class.php

htdocs/compta/facture/class/api_invoices.class.php

htdocs/expensereport/class/api_expensereports.class.php

htdocs/product/class/api_deprecated_product.class.php

htdocs/product/class/api_products.class.php

htdocs/product/stock/class/api_stockmovements.class.php

htdocs/product/stock/class/api_warehouses.class.php

htdocs/projet/class/api_projects.class.php

htdocs/projet/class/api_tasks.class.php