Move some files to a better place, remove some unused file

layouts/partials/posts/math.html

@@ -0,0 +1,24 @@
+{{- if .Params.math -}}
+  <script type="text/javascript" async
+    src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS-MML_HTMLorMML-full">
+    MathJax.Hub.Config({
+      tex2jax: {
+        inlineMath: [['$','$']],
+        displayMath: [['$$','$$']],
+        processEscapes: true,
+        processEnvironments: true,
+        skipTags: ['script', 'noscript', 'style', 'textarea', 'pre'],
+        TeX: { extensions: ["AMSmath.js", "AMSsymbols.js"] }
+      }
+    });
+    MathJax.Hub.Queue(function() {
+      // Fix <code> tags after MathJax finishes running. This is a
+      // hack to overcome a shortcoming of Markdown. Discussion at
+      // https://github.com/mojombo/jekyll/issues/199
+      var all = MathJax.Hub.getAllJax(), i;
+      for(i = 0; i < all.length; i += 1) {
+          all[i].SourceElement().parentNode.className += ' has-jax';
+      }
+    });
+  </script>
+{{- end -}}