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/forum/src/components/PostUser.js

@@ -0,0 +1,100 @@
+import Component from 'flarum/Component';
+import UserCard from 'flarum/components/UserCard';
+import avatar from 'flarum/helpers/avatar';
+import username from 'flarum/helpers/username';
+import listItems from 'flarum/helpers/listItems';
+
+/**
+ * The `PostUser` component shows the avatar and username of a post's author.
+ *
+ * ### Props
+ *
+ * - `post`
+ */
+export default class PostHeaderUser extends Component {
+  constructor(...args) {
+    super(...args);
+
+    /**
+     * Whether or not the user hover card is visible.
+     *
+     * @type {Boolean}
+     */
+    this.cardVisible = false;
+  }
+
+  view() {
+    const post = this.props.post;
+    const user = post.user();
+
+    if (!user) {
+      return (
+        <div className="post-user">
+          <h3>{avatar(user)} {username(user)}</h3>
+        </div>
+      );
+    }
+
+    let card = '';
+
+    if (!post.isHidden() && this.cardVisible) {
+      card = UserCard.component({
+        user,
+        className: 'user-card-popover fade',
+        controlsButtonClassName: 'btn btn-default btn-icon btn-controls btn-naked'
+      });
+    }
+
+    return (
+      <div className="post-user">
+        <h3>
+          <a href={app.route.user(user)} config={m.route}>
+            {avatar(user)} {username(user)}
+          </a>
+        </h3>
+        <ul className="badges">
+          {listItems(user.badges().toArray())}
+        </ul>
+        {card}
+      </div>
+    );
+  }
+
+  config(isInitialized) {
+    if (isInitialized) return;
+
+    let timeout;
+
+    this.$()
+      .on('mouseover', 'h3 a, .user-card', () => {
+        clearTimeout(timeout);
+        timeout = setTimeout(this.showCard.bind(this), 500);
+      })
+      .on('mouseout', 'h3 a, .user-card', () => {
+        clearTimeout(timeout);
+        timeout = setTimeout(this.hideCard.bind(this), 250);
+      });
+  }
+
+  /**
+   * Show the user card.
+   */
+  showCard() {
+    this.cardVisible = true;
+
+    m.redraw();
+
+    setTimeout(() => this.$('.user-card').addClass('in'));
+  }
+
+  /**
+   * Hide the user card.
+   */
+  hideCard() {
+    this.$('.user-card').removeClass('in')
+      .one('transitionend', () => {
+        this.cardVisible = false;
+        m.redraw();
+      });
+  }
+}