Prepare release

packages/zefyr/CHANGELOG.md

-## [0.1.0] - Add release date
+## 0.1.0
 
 *  Initial release.

packages/zefyr/analysis_options.yaml

 analyzer:
-  strong-mode: true
   language:
     enableSuperMixins: true
 

packages/zefyr/example/lib/main.dart

 // 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 'dart:convert';
-import 'dart:io';
 
 import 'package:flutter/material.dart';
 import 'package:quill_delta/quill_delta.dart';

packages/zefyr/pubspec.yaml

 name: zefyr
-description: Flutter widgets for editing rich text.
+description: Rich text editor for Flutter.
 version: 0.1.0
 author: Anatoly Pulyaevskiy <anatoly.pulyaevskiy@gmail.com>
 homepage: https://github.com/pulyaevskiy/zefyr