Add hierarchy utils and use them in search.

pkg/analysis_services/lib/index/local_file_index.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library engine.index.local_file_index;
+library services.index.local_file_index;
 
 import 'dart:io';
 
 import 'package:analysis_services/index/index.dart';
 import 'package:analysis_services/src/index/local_index.dart';
 import 'package:analysis_services/src/index/store/codec.dart';
 import 'package:analysis_services/src/index/store/separate_file_manager.dart';
 import 'package:analysis_services/src/index/store/split_store.dart';
 import 'package:analyzer/src/generated/engine.dart';
 
 
 Index createLocalFileIndex(Directory directory) {
   var fileManager = new SeparateFileManager(directory);
   var stringCodec = new StringCodec();
   var nodeManager = new FileNodeManager(fileManager,
       AnalysisEngine.instance.logger, stringCodec, new ContextCodec(),
       new ElementCodec(stringCodec), new RelationshipCodec(stringCodec));
   return new LocalIndex(nodeManager);
 }