Block level filtering/querying aka another option for searching for things in Drafts

New update: added an explanation for the kind of search this performs. Also added support for backlinks— the initial prompt offers the title of the current draft in two different forms as options for searching for linked and unlinked references.

If you checked out an earlier version of this, note that the most recent update also returns the full body of drafts containing the searched for term/phrase in the title. I may refine that further in the future— open to suggestions.