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/Users/Commands/DeleteAvatarHandler.php

@@ -0,0 +1,59 @@
+<?php namespace Flarum\Core\Users\Commands;
+
+use Flarum\Core\Users\Events\AvatarWillBeDeleted;
+use Flarum\Core\Users\UserRepositoryInterface;
+use Flarum\Core\Support\DispatchesEvents;
+use League\Flysystem\FilesystemInterface;
+
+class DeleteAvatarHandler
+{
+    use DispatchesEvents;
+
+    /**
+     * @var UserRepositoryInterface
+     */
+    protected $users;
+
+    /**
+     * @var FilesystemInterface
+     */
+    protected $uploadDir;
+
+    /**
+     * @param UserRepositoryInterface $users
+     * @param FilesystemInterface $uploadDir
+     */
+    public function __construct(UserRepositoryInterface $users, FilesystemInterface $uploadDir)
+    {
+        $this->users = $users;
+        $this->uploadDir = $uploadDir;
+    }
+
+    /**
+     * @param DeleteAvatar $command
+     * @return \Flarum\Core\Users\User
+     */
+    public function handle(DeleteAvatar $command)
+    {
+        $actor = $command->actor;
+
+        $user = $this->users->findOrFail($command->userId);
+
+        // Make sure the current user is allowed to edit the user profile.
+        // This will let admins and the user themselves pass through, and
+        // throw an exception otherwise.
+        $user->assertCan($actor, 'edit');
+
+        $avatarPath = $user->avatar_path;
+        $user->changeAvatarPath(null);
+
+        event(new AvatarWillBeDeleted($user, $actor));
+
+        $this->uploadDir->delete($avatarPath);
+
+        $user->save();
+        $this->dispatchEventsFor($user);
+
+        return $user;
+    }
+}