Merge branch 'gh-pages' of github.com:swcarpentry/styles into analytics

_includes/episode_navbar.html

 {% comment %}
   Find previous and next episodes (if any).
-  Including file must pass episode_navbar_title=true or ...=false to display episode title.
 {% endcomment %}
 {% for episode in site.episodes  %}
   {% if episode.url == page.url %}
@@ -21,9 +20,9 @@
   <div class="col-md-1">
     <h3>
       {% if prev_episode %}
-      <a href="{{ page.root }}{{ prev_episode.url }}"><span class="glyphicon glyphicon-menu-left"></span></a>
+      <a href="{{ page.root }}{{ prev_episode.url }}"><span class="glyphicon glyphicon-menu-left" aria-hidden="true"></span><span class="sr-only">previous episode</span></a>
       {% else %}
-      <a href="{{ page.root }}/"><span class="glyphicon glyphicon-menu-up"></span></a>
+      <a href="{{ page.root }}/"><span class="glyphicon glyphicon-menu-up" aria-hidden="true"></span><span class="sr-only">lesson home</span></a>
       {% endif %}
     </h3>
   </div>
@@ -36,9 +35,9 @@
   <div class="col-md-1">
     <h3>
       {% if next_episode %}
-      <a href="{{ page.root }}{{ next_episode.url }}"><span class="glyphicon glyphicon-menu-right"></span></a>
+      <a href="{{ page.root }}{{ next_episode.url }}"><span class="glyphicon glyphicon-menu-right" aria-hidden="true"></span><span class="sr-only">next episode</span></a>
       {% else %}
-      <a href="{{ page.root }}/"><span class="glyphicon glyphicon-menu-up"></span></a>
+      <a href="{{ page.root }}/"><span class="glyphicon glyphicon-menu-up" aria-hidden="true"></span><span class="sr-only">lesson home</span></a>
       {% endif %}
     </h3>
   </div>

_includes/javascript.html

 <script src="{{ page.root }}/assets/js/jquery.min.js"></script>
 <script src="{{ page.root }}/assets/js/bootstrap.min.js"></script>
 <script src="{{ page.root }}/assets/js/lesson.js"></script>
+<script>
+  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+  })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+  ga('create', 'UA-37305346-2', 'auto');
+  ga('send', 'pageview');
+</script>

_includes/navbar.html

@@ -68,7 +68,7 @@
       </ul>
       <form class="navbar-form navbar-right" role="search" id="search" onsubmit="google_search(); return false;">
         <div class="form-group">
-          <input type="text" id="google-search" placeholder="Search...">
+          <input type="text" id="google-search" placeholder="Search..." aria-label="Google site search">
         </div>
       </form>
     </div>

_layouts/base.html

@@ -7,7 +7,8 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta http-equiv="last-modified" content="{{ site.time }}">
     <meta name="viewport" content="width=device-width, initial-scale=1">
-    <meta name="search-domain" value="{{ page.root }}">
+    <!-- meta "search-domain" used for google site search function google_search() -->
+    <meta name="search-domain" value="{{ site.github.url }}">
     <link rel="stylesheet" type="text/css" href="{{ page.root }}/assets/css/bootstrap.css" />
     <link rel="stylesheet" type="text/css" href="{{ page.root }}/assets/css/bootstrap-theme.css" />
     <link rel="stylesheet" type="text/css" href="{{ page.root }}/assets/css/lesson.css" />