[smartplaylist] adds routine for generating queries against videodb link tables
[videodb] add routines for creating link indices
[videodb] refactors UpdateActorLinkTable into UpdateActorLinksToItem, AddActorLinksToItem, with special case for musicvideos
[videodb] switch actor table and links to the new layout
[videodb] cleanup AddCast, AddLinkToActor to drop unused params
[videodb] refactor UpdateLinkTable into AddLinksToItem, UpdateLinksToItem, and use these when adding genre,country,studio
[videodb] switch the studio,genre,country and link tables to the new format
[videodb] switch the tag and link tables to the new layout
[videodb] simplify AddToLinkTable, RemoveFromLinkTable implementations
[videodb] adds AppendFilter() to simplify repetitive queries in GetFilter
[videodb] FIX: drop incorrect querying of non-existent setlinkmovie table
[videodb] use type_view for views