update packages and add valign

scripts/reveal.js/dist/utils/loader.d.ts

@@ -0,0 +1,8 @@
+/**
+ * Loads a JavaScript file from the given URL and executes it.
+ *
+ * @param {string} url Address of the .js file to load
+ * @param {function} callback Method to invoke when the script
+ * has loaded and executed
+ */
+export declare const loadScript: (url: string, callback?: (error?: Error) => void) => void;