Currently (into to from) preserves to's metadata but discards from's metadata. The enhancement would be to have 'into' do something like (merge (meta to) (meta from)). Justification: as with data, so with metadata. Use case: Using deftype, I have a class EntityMap that clojurizes a native Java class (App Engine's Entity class), making it behave just like a clojure map. This includes using into to convert an EntityMap to an ordinary PersistentMap; the problem is that key information for the EntityMap is really metadata, so I need (into {} em) to put that metadata into the new PersistentMap.
See also CLJ-916
