Adds navigation highlighting of current view

All h1 and h2 elements, that are in the current viewport
will trigger adding an .active class to the corresponding
entry in the navigation.

styles/site/site-navigation.less

@@ -30,6 +30,9 @@
         text-decoration: none;
     }
 }
+.site-navigation a.active{
+	background-color: #ff9;
+}
 .site-navigation ul ul{
     .mls;
     .pth;