Panels js and css caching

Hello,

Js and css caching in the 7.x branch isn't work properly, as long as it uses code relevant only for Drupal 6.
drupal_add_js function now returns array of a different structure, so that scripts aren't cached properly. Same thing with css, signature of drupal_add_css function has been changed, and now it accepts only two parameters.
Also creating of panels_cache_object instance was moved above the content render, in order to store previously added js/css and cache only those, added during the panel render.

I made a patch which solves this issue, please review it when you have time.

Thanks,
Dmitry