update piwik code

This is simply a newer version of the code.  Additionally I have enabled these two options:
* Track visitors across all subdomains of kwant
* Prepend the site domain to the page title when tracking

conf.py

@@ -917,18 +917,18 @@ BODY_END = """
   var _paq = _paq || [];
   _paq.push(["setDocumentTitle", document.domain + "/" + document.title]);
   _paq.push(["setCookieDomain", "*.kwant-project.org"]);
-  _paq.push(["trackPageView"]);
-  _paq.push(["enableLinkTracking"]);
-
+  _paq.push(["setDomains", ["*.kwant-project.org","*.downloads.kwant-project.org","*.git.kwant-project.org","*.gitlab.kwant-project.org"]]);
+  _paq.push(['trackPageView']);
+  _paq.push(['enableLinkTracking']);
   (function() {
-    var u=(("https:" == document.location.protocol) ? "https" : "http") + "://piwik.kwant-project.org/";
-    _paq.push(["setTrackerUrl", u+"piwik.php"]);
-    _paq.push(["setSiteId", "1"]);
-    var d=document, g=d.createElement("script"), s=d.getElementsByTagName("script")[0]; g.type="text/javascript";
-    g.defer=true; g.async=true; g.src=u+"piwik.js"; s.parentNode.insertBefore(g,s);
+    var u="//piwik.kwant-project.org/";
+    _paq.push(['setTrackerUrl', u+'piwik.php']);
+    _paq.push(['setSiteId', 1]);
+    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+    g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
   })();
 </script>
-<noscript><img src="http://piwik.kwant-project.org/piwik.php?idsite=1&amp;rec=1" style="border:0" alt="" /></noscript>
+<noscript><p><img src="//piwik.kwant-project.org/piwik.php?idsite=1" style="border:0;" alt="" /></p></noscript>
 <!-- End Piwik Code: Analytics are used by us to improve the site, and not sent to anyone. -->
 """