Strict warning: Only variables should be passed by reference

Thanks for this handy little module. It's just what I need, since it allows me to use the Flippy pager on the top node.

The module throws the following strict warning with PHP 5.5.

Strict warning: Only variables should be passed by reference in top_node_plugin_style_full_node->render() (line 24 of top_node_plugin_style_full_node.inc).

I've rolled a patch that fixes it.