Several fix in warehouse stock change (rounding, api rest)

htdocs/api/class/api.class.php

htdocs/categories/class/api_categories.class.php

htdocs/core/lib/functions.lib.php

htdocs/product/stock/card.php

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

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

htdocs/product/stock/class/mouvementstock.class.php

htdocs/product/stock/mouvement.php