Move a bunch of src/ files into subdirectories.

lib/src/runner/load_exception.dart

Index: lib/src/runner/load_exception.dart
diff --git a/lib/src/load_exception.dart b/lib/src/runner/load_exception.dart
similarity index 95%
rename from lib/src/load_exception.dart
rename to lib/src/runner/load_exception.dart
index 8c6dff0d48073409e429c7baf6f385c1aaaebf22..f2bc2f1ef8daa460b6367554e611703b42a194ca 100644
--- a/lib/src/load_exception.dart
+++ b/lib/src/runner/load_exception.dart
@@ -2,13 +2,13 @@
 // 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.load_exception;
+library unittest.runner.load_exception;
 
 import 'dart:isolate';
 
 import 'package:path/path.dart' as p;
 
-import 'utils.dart';
+import '../utils.dart';
 
 class LoadException implements Exception {
   final String path;