Massive refactor

- Use contextual namespaces within Flarum\Core
- Clean up and docblock everything
- Refactor Activity/Notification blueprint stuff
- Refactor Formatter stuff
- Refactor Search stuff
- Upgrade to JSON-API 1.0
- Removed “addedPosts” and “removedPosts” relationships from discussion
API. This was used for adding/removing event posts after renaming a
discussion etc. Instead we should make an additional request to get all
new posts

Todo:
- Fix Extenders and extensions
- Get rid of repository interfaces
- Fix other bugs I’ve inevitably introduced

src/Core/Posts/Commands/EditPostHandler.php

@@ -0,0 +1,65 @@
+<?php namespace Flarum\Core\Posts\Commands;
+
+use Flarum\Core\Posts\PostRepositoryInterface;
+use Flarum\Core\Posts\Events\PostWillBeSaved;
+use Flarum\Core\Support\DispatchesEvents;
+use Flarum\Core\Posts\CommentPost;
+
+class EditPostHandler
+{
+    use DispatchesEvents;
+
+    /**
+     * @var PostRepositoryInterface
+     */
+    protected $posts;
+
+    /**
+     * @param PostRepositoryInterface $posts
+     */
+    public function __construct(PostRepositoryInterface $posts)
+    {
+        $this->posts = $posts;
+    }
+
+    /**
+     * @param EditPost $command
+     * @return \Flarum\Core\Posts\Post
+     * @throws \Flarum\Core\Exceptions\PermissionDeniedException
+     */
+    public function handle(EditPost $command)
+    {
+        $actor = $command->actor;
+        $data = $command->data;
+
+        $post = $this->posts->findOrFail($command->postId, $actor);
+
+        if ($post instanceof CommentPost) {
+            $attributes = array_get($data, 'attributes', []);
+
+            if (isset($attributes['content'])) {
+                $post->assertCan($actor, 'edit');
+
+                $post->revise($attributes['content'], $actor);
+            }
+
+            if (isset($attributes['isHidden'])) {
+                $post->assertCan($actor, 'edit');
+
+                if ($attributes['isHidden']) {
+                    $post->hide($actor);
+                } else {
+                    $post->restore();
+                }
+            }
+        }
+
+        event(new PostWillBeSaved($post, $actor, $data));
+
+        $post->save();
+
+        $this->dispatchEventsFor($post);
+
+        return $post;
+    }
+}