[NodeInfo] New endpoint and formula for computing active users

Seriously improved documentation
Now NodeInfo 2.0 is available at /api/nodeinfo/2.0.json
For active users we now also consider favourites and recently created accounts
Some further minor bug fixes and full review of the implementation

plugins/Nodeinfo/actions/nodeinfojrd.php

@@ -1,9 +1,36 @@
 <?php
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
 
-if (!defined('GNUSOCIAL')) {
-    exit(1);
-}
+/**
+ * Provided in /.well-known/nodeinfo
+ *
+ * @package   NodeInfo
+ * @author    Stéphane Bérubé <chimo@chromic.org>
+ * @copyright 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
 
+defined('GNUSOCIAL') || die();
+
+/**
+ * JRD document for NodeInfo
+ *
+ * @copyright 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
 class NodeinfoJRDAction extends XrdAction
 {
     const NODEINFO_2_0_REL = 'http://nodeinfo.diaspora.software/ns/schema/2.0';