[ActivityPub] Handle DELETE-Person activity

ActivityPubPlugin:
- update grab_notice_from_url to make online grab optional
- subscribe events of user and profile deletion
- bump minor version number

Activitypub_inbox_handler:
- separate handle_delete for delete-note and delete-person

Activitypub_postman:
- add delete-person logic

Activitypub_delete:
- update validation method to check for the "Person" type
- update to_array method to target the activity

plugins/ActivityPub/lib/models/Activitypub_delete.php

@@ -48,10 +48,11 @@ class Activitypub_delete
     {
         $res = [
             '@context' => 'https://www.w3.org/ns/activitystreams',
-            'id'     => $object.'/delete',
-            'type'   => 'Delete',
-            'actor'  => $actor,
-            'object' => $object
+            'id'       => $object.'/delete',
+            'type'     => 'Delete',
+            'to'       => ['https://www.w3.org/ns/activitystreams#Public'],
+            'actor'    => $actor,
+            'object'   => $object
         ];
         return $res;
     }
@@ -73,10 +74,10 @@ class Activitypub_delete
         } else {
             if (!isset($object['type'])) {
                 throw new Exception('Object type was not specified for Delete Activity.');
-            } else if ($object['type'] !== "Tombstone") {
+            }
+            if ($object['type'] !== "Tombstone" && $object['type'] !== "Person") {
                 throw new Exception('Invalid Object type for Delete Activity.');
             }
-
             if (!isset($object['id'])) {
                 throw new Exception('Object id was not specified for Delete Activity.');
             }