* use column_*() methods
* remove extra arguments from single_row()
* introduce derived class WP_Post_Comments_Table for handling the post metabox comments
* use $pending_count property instead of $_comment_pending_count global
See #14579
git-svn-id: http://svn.automattic.com/wordpress/trunk@15630 1a063a9b-81f0-0310-95a4-ce76da25c4cd