wp_category_checklist() function generates damaged category tree

[codestyling]

While writing/editing posts the GUI shows all categories available using a tree view inside a special box. But this view gets logical damaged, if the post has already assigned categories. Some child categories not been used will not longer be shown related to it's parent but at the end of tree in linear order.

I described and illustrated it with serveral images here:  http://www.code-styling.de/english/wordpress-category-tree-chaos-at-write-posts My quick solution was commenting the pre-filter loop to get a correct tree view. May be a more sophisticated solution will be needed.

See #7000