message: Escape should cancel a reply
diff: @@ -131,8 +131,13 @@ export default class SendMessageComposer extends React.Component {
  this.onVerticalArrow(event, false);
  } else if (this._prepareToEncrypt) {
  this._prepareToEncrypt();
  + } else if (event.key === Key.ESCAPE) {
  + dis.dispatch({
  + action: 'reply_to_event',
  + event: null,
  + });
  }
  - }
  + };
  onVerticalArrow(e, up) {
  // arrows from an initial-caret composer navigates recent messages to edit
  