message: reapply pills, link preview, code highlighting, ... after edit
diff: @@ -88,7 +88,10 @@ module.exports = React.createClass({
  componentDidMount: function() {
  this._unmounted = false;
  + this._applyFormatting();
  + },
  + _applyFormatting() {
  // pillifyLinks BEFORE linkifyElement because plain room/user URLs in the composer
  // are still sent as plaintext URLs. If these are ever pillified in the composer,
  // we should be pillify them here by doing the linkifying BEFORE the pillifying.
  @@ -123,7 +126,11 @@ module.exports = React.createClass({
  }
  },
  - componentDidUpdate: function() {
  + componentDidUpdate: function(prevProps) {
  + const messageWasEdited = prevProps.replacingEventId !== this.props.replacingEventId;
  + if (messageWasEdited) {
  + this._applyFormatting();
  + }
  this.calculateUrlPreview();
  },
  