Multiple category tags support

[ecampver]

It is not possible to add multiple category tags right now. I needed this feature and modified Rss.php a little bit. What I did was changing line 112:

$elem_item->addCdataChild($options[0], $vI);

by this:

if (is_array($vI)) {
    foreach ($vI as $v) {
        $elem_item->addCdataChild($options[0], $v);
    }
} else {
    $elem_item->addCdataChild($options[0], $vI);
}

and added category|cdata to every item as an array. Does this make any sense?