reveal.js plugin flow now uses promises, refactor markdown plugin to use promises

js/reveal.js

@@ -546,7 +546,7 @@
 			// If the plugin has an 'init' method, initialize and
 			// wait for the callback
 			if( typeof plugin.init === 'function' ) {
-				plugin.init( function() {
+				plugin.init().then( function() {
 					if( --pluginsToInitialize === 0 ) {
 						loadAsyncDependencies();
 					}
@@ -1551,11 +1551,21 @@
 
 	/**
 	 * Registers a new plugin with this reveal.js instance.
+	 *
+	 * reveal.js waits for all regisered plugins to initialize
+	 * before considering itself ready, as long as the plugin
+	 * is registered before calling `Reveal.initialize()`.
 	 */
 	function registerPlugin( id, plugin ) {
 
 		plugins[id] = plugin;
 
+		// If a plugin is registered after reveal.js is loaded,
+		// initialize it right away
+		if( loaded && typeof plugin.init === 'function' ) {
+			plugin.init();
+		}
+
 	}
 
 	/**
@@ -5841,6 +5851,11 @@
 			return dom.wrapper || document.querySelector( '.reveal' );
 		},
 
+		// Returns a hash with all registered plugins
+		getPlugins: function() {
+			return plugins;
+		},
+
 		// Returns true if we're currently on the first slide
 		isFirstSlide: function() {
 			return ( indexh === 0 && indexv === 0 );