fix issue with auto-advance (closes #273)

js/reveal.js

@@ -958,7 +958,8 @@ var Reveal = (function(){
 			var slideAutoSlide = slides[index].getAttribute( 'data-autoslide' );
 			if( slideAutoSlide ) {
 				autoSlide = parseInt( slideAutoSlide, 10 );
-			} else {
+			} 
+			else {
 				autoSlide = config.autoSlide;
 			}
 
@@ -1165,7 +1166,7 @@ var Reveal = (function(){
 
 			// If this is a vertical slide, grab the vertical index
 			if( isVertical ) {
-				v = Math.max( toArray( slide.parentNode.children ).indexOf( slide ), 0 );
+				v = Math.max( toArray( slide.parentNode.querySelectorAll( 'section' ) ).indexOf( slide ), 0 );
 			}
 		}