PHP 5.4, passing args by reference and "panels_everywhere_theme_registry_alter()"

I'm playing with Panels & Panels Everywhere on my localhost and I'm using PHP 5.4.9. It looks like in PHP 5.4.9, it is required to put the ampersand explicitly in the definition of a function, if you want it to receive arguments by reference when called by call_user_func_array. This probably affects loads of functions in contrib. Worst of all, PHP fails silently, which is stupid - it was supposed to fail with a fatal error. Docs: PHP, passing by reference, where the comments shed some light on this.

My current issue is with panels_everywhere_theme_registry_alter(), which requires its ampersand too (it's called inside drupal_alter(), which uses PHP's call_user_func_array()). So here's a patch that adds it.