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/components/Dropdown.js

@@ -0,0 +1,69 @@
+import Component from 'flarum/Component';
+import icon from 'flarum/helpers/icon';
+import listItems from 'flarum/helpers/listItems';
+
+/**
+ * The `Dropdown` component displays a button which, when clicked, shows a
+ * dropdown menu beneath it.
+ *
+ * ### Props
+ *
+ * - `buttonClassName` A class name to apply to the dropdown toggle button.
+ * - `menuClassName` A class name to apply to the dropdown menu.
+ * - `icon` The name of an icon to show in the dropdown toggle button. Defaults
+ *   to 'ellipsis-v'.
+ * - `label` The label of the dropdown toggle button. Defaults to 'Controls'.
+ *
+ * The children will be displayed as a list inside of the dropdown menu.
+ */
+export default class Dropdown extends Component {
+  static initProps(props) {
+    props.className = props.className || '';
+    props.buttonClassName = props.buttonClassName || '';
+    props.contentClassName = props.contentClassName || '';
+    props.icon = props.icon || 'ellipsis-v';
+    props.label = props.label || app.trans('controls');
+  }
+
+  view() {
+    return (
+      <div className={'dropdown btn-group ' + this.props.className}>
+        {this.getButton()}
+        <ul className={'dropdown-menu ' + this.props.menuClassName}>
+          {listItems(this.props.children)}
+        </ul>
+      </div>
+    );
+  }
+
+  /**
+   * Get the template for the button.
+   *
+   * @return {*}
+   * @protected
+   */
+  getButton() {
+    return (
+      <a href="javascript:;"
+        className={'dropdown-toggle ' + this.props.buttonClassName}
+        data-toggle="dropdown"
+        onclick={this.props.onclick}>
+        {this.getButtonContent()}
+      </a>
+    );
+  }
+
+  /**
+   * Get the template for the button's content.
+   *
+   * @return {*}
+   * @protected
+   */
+  getButtonContent() {
+    return [
+      icon(this.props.icon),
+      <span className="label">{this.props.label}</span>,
+      icon('caret-down', {className: 'caret'})
+    ];
+  }
+}