patch to allow multiplexing on URL load

plugin/multiplex/master.js

@@ -19,6 +19,9 @@
 
 	};
 
+	// post once the page is loaded, so the client follows also on "open URL".
+	window.onload = post;
+
 	// Monitor events that trigger a change in state
 	Reveal.addEventListener( 'slidechanged', post );
 	Reveal.addEventListener( 'fragmentshown', post );
@@ -28,4 +31,4 @@
 	Reveal.addEventListener( 'paused', post );
 	Reveal.addEventListener( 'resumed', post );
 
-}());
\ No newline at end of file
+}());