Extract `tagged_editions` table to a partial
Add filtering to topic pages
Fix failing ClassificationFeaturingsController test
Adding functional tests for filtering
Remove unused code

This method (and the scopes it depends on) are not being used anywhere
in the codebase.
Remove external link tracking

This was added to get analytics on traffic from specialist guides (now
detailed guidance) to organisation homepages when the organisations
linked in the metadata of those pages were all external. As those links
are all internal this is no longer needed.

Also this way of tracking external links is really very evil.
Scenarios for filtering featured documents on topics
Add need_ids attribute to detailed guides
Detailed guides: show goals for associated needs
Editing need ids for detailed guides
Validate that detailed guide need ids are 6 digits
Simplify PanopticonRegisterArtefactWorkerTest with test helper
Register need_ids with panopticon for detailed guides
Fix creation and editing of detailed guides w/o need_ids
Det guides: prompt user for comma-separated need ids
Show detailed guides needs in their entirety

As a <c>,
I need to <d>,
So that <e>
Push #need_ids down to Edition
Add functional test for associating need_ids for detailed guides
Add Maslow deep-link for detailed guides needs
Increase coverate around method being refactored