plugin consistency

plugin/highlight/highlight.js

@@ -5,7 +5,7 @@ import './highlight-line-numbers.js'
  * reveal.js plugin that adds syntax highlight support.
  */
 
-let Plugin = {
+const Plugin = {
 
 	id: 'highlight',
 

plugin/notes/notes.js

@@ -9,7 +9,7 @@
  * 3. This window proceeds to send the current presentation state
  *    to the notes window
  */
-let Plugin = (function() {
+const Plugin = () => {
 
     var notesPopup = null;
 
@@ -180,6 +180,6 @@ let Plugin = (function() {
 		open: openNotes
 	};
 
-})();
+};
 
-export default () => Plugin;
+export default Plugin;

plugin/zoom/zoom.js

@@ -1,7 +1,7 @@
 /*!
  * reveal.js Zoom plugin
  */
-var Plugin = {
+const Plugin = {
 
 	id: 'zoom',