Add breaking changes and release 1.0.0.

test/error_test.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.
 
 import 'package:string_scanner/string_scanner.dart';
 import 'package:test/test.dart';
 
 import 'utils.dart';
 
 void main() {
@@ skipping 41 matching lines @@
       scanner.expect('foo ');
       scanner.expect('bar');
       var match = scanner.lastMatch;
       scanner.position = 0;
       expect(() => scanner.error('oh no!', match: match),
           throwsStringScannerException('bar'));
     });
   });
 
   group("with position and/or length", () {
-    test('defaults to length 1', () {
+    test('defaults to length 0', () {
       var scanner = new StringScanner('foo bar baz');
       scanner.expect('foo ');
       expect(() => scanner.error('oh no!', position: 1),
-          throwsStringScannerException('o'));
+          throwsStringScannerException(''));
     });
 
     test('defaults to the current position', () {
       var scanner = new StringScanner('foo bar baz');
       scanner.expect('foo ');
       expect(() => scanner.error('oh no!', length: 3),
           throwsStringScannerException('bar'));
     });
 
     test('supports an earlier position', () {
@@ skipping 61 matching lines @@
     test("if position + length is outside the string", () {
       expect(() => scanner.error("oh no!", position: 7, length: 7),
           throwsArgumentError);
     });
 
     test("if length is negative", () {
       expect(() => scanner.error("oh no!", length: -1), throwsArgumentError);
     });
   });
 }