Move ToC initialization code into own js file

static/js/main.js

@@ -0,0 +1,22 @@
+window.onload = function() {
+  var container = document.querySelector('#toc');
+
+  var selector = "h2";
+  if (container.className.split(" ").indexOf("coarse") == -1) {
+    selector += ",h3";
+  }
+
+  var toc = initTOC({
+      selector: selector,
+      scope: '.post',
+      overwrite: false,
+      prefix: 'toc'
+  });
+
+  var heading = document.createElement("H2");
+  var heading_text = document.createTextNode("Table of Contents");
+  heading.appendChild(heading_text);
+
+  container.appendChild(heading);
+  container.appendChild(toc);
+}