Massive JavaScript cleanup

- Use JSX for templates
- Docblock/comment everything
- Mostly passes ESLint (still some work to do)
- Lots of renaming, refactoring, etc.

CSS hasn't been updated yet.

js/lib/initializers/humanTime.js

@@ -0,0 +1,18 @@
+import humanTimeUtil from 'flarum/utils/humanTime';
+
+function updateHumanTimes() {
+  $('[data-humantime]').each(function() {
+    const $this = $(this);
+    const ago = humanTimeUtil($this.attr('datetime'));
+
+    $this.html(ago);
+  });
+}
+
+/**
+ * The `humanTime` initializer sets up a loop every 1 second to update
+ * timestamps rendered with the `humanTime` helper.
+ */
+export default function humanTime() {
+  setInterval(updateHumanTimes, 1000);
+}