Add bootstrap Sphinx theme

doc/bootstrap/navbartoc.html

@@ -0,0 +1,10 @@
+<li class="dropdown">
+  <a role="button"
+     id="dLabelLocalToc"
+     data-toggle="dropdown"
+     data-target="#"
+     href="#">{{ _(theme_navbar_pagenav_name) }} <b class="caret"></b></a>
+  <ul class="dropdown-menu localtoc"
+      role="menu"
+      aria-labelledby="dLabelLocalToc">{{ toc }}</ul>
+</li>