Add flattr button

Author: lefticus

_includes/header.html

@@ -63,6 +63,9 @@
 <div class="hidden-print">
   <div class="container">
     <ul class="list-inline">
+      <li>
+        <script id='fb42tzq'>(function(i){var f,s=document.getElementById(i);f=document.createElement('iframe');f.src='//api.flattr.com/button/view/?uid=lefticus&button=compact&url='+encodeURIComponent(document.URL);f.title='Flattr';f.height=20;f.width=110;f.style.borderWidth=0;s.parentNode.insertBefore(f,s);})('fb42tzq');</script>
+      </li>
       <li>
       <iframe class="github-btn" src="http://ghbtns.com/github-btn.html?user=ChaiScript&repo=ChaiScript&type=watch&count=true" allowtransparency="true" frameborder="0" scrolling="0" width="100px" height="20px"></iframe>
       </li>