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/alerts.js

@@ -1,32 +1,68 @@
-import Component from 'flarum/component';
+import Component from 'flarum/Component';
+import Alert from 'flarum/components/Alert';
 
+/**
+ * The `Alerts` component provides an area in which `Alert` components can be
+ * shown and dismissed.
+ */
 export default class Alerts extends Component {
-  constructor(props) {
-    super(props);
+  constructor(...args) {
+    super(...args);
 
+    /**
+     * An array of Alert components which are currently showing.
+     *
+     * @type {Alert[]}
+     * @protected
+     */
     this.components = [];
   }
 
   view() {
-    return m('div.alerts', this.components.map((component) => {
-      component.props.ondismiss = this.dismiss.bind(this, component);
-      return m('div.alert-wrapper', component);
-    }));
+    return (
+      <div className="alerts">
+        {this.components.map(component => <div className="alerts-item">{component}</div>)}
+      </div>
+    );
   }
 
+  /**
+   * Show an Alert in the alerts area.
+   *
+   * @param {Alert} component
+   * @public
+   */
   show(component) {
+    if (!(component instanceof Alert)) {
+      throw new Error('The Alerts component can only show Alert components');
+    }
+
+    component.props.ondismiss = this.dismiss.bind(this, component);
+
     this.components.push(component);
     m.redraw();
   }
 
+  /**
+   * Dismiss an alert.
+   *
+   * @param {Alert} component
+   * @public
+   */
   dismiss(component) {
-    var index = this.components.indexOf(component);
+    const index = this.components.indexOf(component);
+
     if (index !== -1) {
       this.components.splice(index, 1);
       m.redraw();
     }
   }
 
+  /**
+   * Clear all alerts.
+   *
+   * @public
+   */
   clear() {
     this.components = [];
     m.redraw();