Support discovery of unregistered post types

[bobbingwide]

On some sites custom post type data is created in wp_posts using a plugin or theme which is then deactivated. For security reasons the site no longer displays any UI for the content - admin or front-end.

It would be nice if this data could be discovered by oik-types. It would come in handy when upgrading a site and switching between plugins and themes.
In my current example, content was created using an event manager plugin.

The following SQL provided the details of the missing post types.

SELECT count(*), post_type FROM `wp_posts` group by post_type order by 1 desc

It turns out I was looking for tribe_events.

count(*)	post_type
482	revision
71	attachment
47	post
32	bp-email
29	clink
25	page
13	dpw_email
11	nav_menu_item
7	forum
6	topic
6	customize_changeset
4	tribe_events
3	tribe_venue
3	reply
3	tribe_organizer
2	oembed_cache
1	meetup