Make get_editable_user_ids() use the role system instead of user level

[garyc40]

The function get_editable_user_ids() is used to populate the Author list in Post Edit admin page. Currently, it uses user levels to determine which users have permission to edit posts.

This is a deprecated approach. Role management plugins have no way to intercept this function, so even though, say, subscribers are assigned enough capabilities to edit / publish posts, these users are not listed in the Author list. This is also troublesome for custom post types that allow subscribers or custom roles to post and edit contents.

Attached is a patch to fix this and make get_editable_user_ids() use the role system instead.

[scribu]

get_editable_user_ids() is deprecated in trunk so fixing it is not necessary anymore.

See #14572.