Provide back compat mapping for user_level, wp_usersettings and...

Provide back compat mapping for user_level, wp_usersettings and wp_usersettingstime properties of WP_User objects. Fixes #19265.


git-svn-id: https://core.svn.wordpress.org/trunk@19325 1a063a9b-81f0-0310-95a4-ce76da25c4cd