Throw error if NULL libraryID is passed to DataObjects.getByLibraryAndKey()
Use only keys for collections and saved searches in search conditions

Previously, 'collection' and 'savedSearch' conditions used
"[libraryID]_[key]" format. Now, the condition should contain only a
key, and the libraryID will be drawn from either the search itself or a
libraryID search condition. Old-style conditions are still parsed if
provided.