Move a bunch of src/ files into subdirectories.

lib/src/runner/loader.dart

 // Copyright (c) 2015, 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 unittest.loader;
+library unittest.runner.loader;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
 import 'package:path/path.dart' as p;
 
-import 'dart.dart';
-import 'io.dart';
+import '../backend/suite.dart';
+import '../util/dart.dart';
+import '../util/io.dart';
+import '../util/remote_exception.dart';
 import 'isolate_test.dart';
 import 'load_exception.dart';
-import 'remote_exception.dart';
-import 'suite.dart';
 
 /// A class for finding test files and loading them into a runnable form.
 class Loader {
   /// The package root to use for loading tests, or `null` to use the automatic
   /// root.
   final String _packageRoot;
 
   /// All isolates that have been spun up by the loader.
   final _isolates = new Set<Isolate>();
 
@@ skipping 29 matching lines @@
     var packageRoot = _packageRoot == null
         ? p.join(p.dirname(path), 'packages')
         : _packageRoot;
 
     if (!new Directory(packageRoot).existsSync()) {
       throw new LoadException(path, "Directory $packageRoot does not exist.");
     }
 
     var receivePort = new ReceivePort();
     return runInIsolate('''
-import "package:unittest/src/vm_listener.dart";
+import "package:unittest/src/runner/vm_listener.dart";
 
 import "${p.toUri(p.absolute(path))}" as test;
 
 void main(_, Map message) {
   var sendPort = message['reply'];
   VmListener.start(sendPort, () => test.main);
 }
 ''', {
       'reply': receivePort.sendPort
     }, packageRoot: packageRoot).catchError((error, stackTrace) {
@@ skipping 20 matching lines @@
 
   /// Closes the loader and releases all resources allocated by it.
   Future close() {
     for (var isolate in _isolates) {
       isolate.kill();
     }
     _isolates.clear();
     return new Future.value();
   }
 }