Dynamically remove unused tags

[hemidactylus]

It seems that tags with no associated entries (anymore, I guess) still show up on the filters menu on the left.
It would be nice to silently erase them at each data ingestion/refresh to keep it tidier (and amend typos, etc etc).

[synedra]

Actually the problem is that you clicked on a different header. If you're on the home page it shows up. I'd like to add a function where I show on the top buttons how many active pages are underneath. Right now, it just filters the things on the page you're looking at, so it's pretty easy to get no results.