add experimental "+1" button

doc/_templates/layout.html

@@ -1,5 +1,9 @@
 {% extends "!layout.html" %}
 
+{% block relbaritems %}
+{{ super() }}
+<g:plusone></g:plusone>
+{% endblock %}
 
 {% block footer %}
 {{ super() }}
@@ -16,4 +20,5 @@
   })();
 
 </script>
+<script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script>
 {% endblock %}

doc/_templates/localtoc.html

@@ -18,7 +18,7 @@
 <td>
         <a href="{{ pathto('index') }}">home</a>
 </td><td>
-        <a href="{{ pathto('contents') }}">TOC contents</a>
+        <a href="{{ pathto('contents') }}">TOC/contents</a>
 </td></tr><tr><td>
         <a href="{{ pathto('getting-started') }}">install</a>
 </td><td>