Keyboard shortcuts for mail and a shortcut list, offline help and refresh on return, push alerts for new mail

public/index.html

@@ -80,6 +80,7 @@
 <script src="/signal-view.js"></script>
 <script src="/mail.js"></script>
 <script src="/share.js"></script>
+<script src="/keys.js"></script>
 <script src="/boot.js"></script>
 <script src="/shell.js"></script>
 </body>