Ability to scan across multiple libraries at once, with a single gaps list at the end

[EnSt0rm]

Feature request:

I keep movies in a few different libraries, including some separation between target audience, e.g. 'Movies', 'Kids Movies'.

In some instances, part of a collection is within Movies, while another part is in Kids Movies. Across the combined libraries, I have all movies in the collection, but when scanning each library separately, I'll get recommendations for movies from the other library to complete the full collection in each library, rather than seeing that across the entire Server, the collection is already complete.