[-]BO: fix use of parameter class for renderForm()

In renderForm() and form.tpl, we can't use the parameter "class" for simple textarea instead of "textarea-autosize".
A "class" cannot be applied to a "textarea" if it has not the "class" autoload_rte.


To fix it, i propose: 
class="{if isset($input.autoload_rte) && $input.autoload_rte}rte autoload_rte {if isset($input.class)}{$input.class}{/if}{else}{if isset($input.class)}{$input.class}{else}textarea-autosize{/if}{/if}"

Best regards