head: add matomo tracking code

Author: avivace

theme/head.hbs

@@ -10,3 +10,19 @@
 
 <!-- MathML polyfill for Chrome -->
 <script src="https://fred-wang.github.io/mathml.css/mspace.js"></script>
+
+<!-- Matomo tracking code -->
+<script>
+  var _paq = window._paq = window._paq || [];
+  /* tracker methods like "setCustomDimension" should be called before "trackPageView" */
+  _paq.push(['trackPageView']);
+  _paq.push(['enableLinkTracking']);
+  (function() {
+    var u="//stats.gbdev.io/";
+    _paq.push(['setTrackerUrl', u+'matomo.php']);
+    _paq.push(['setSiteId', '1']);
+    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+    g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);
+  })();
+</script>
+<!-- End Matomo Code -->