Fixed calendar top position bug for current versions of jQuery.

Is this project even still alive? I needed an up-to-date version for some outdated JavaScript files but an up-to-date jQuery library. I added halfbaked's fix from the bug tracker which fixes the "position top" bug that started cropping up in jQuery 1.8.0+. I'm not sure if the fix now breaks the legacy libraries, but who cares? Out with the old, in with the new.