Tidying up getUser calls to profiles and some events

getUser calls are much more strict, and one place where this was found was
in the (un)subscribe start/end event handlers, which resulted in making the
Subscription class a bit stricter, regarding ::start and ::cancel at least.
Several minor fixes in many files were made due to this.

This does NOT touch the Foreign_link function, which should also have a more
strict getUser call. That is a future project.

lib/nosuchuserexception.php

@@ -0,0 +1,69 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * class for an exception when a local user is not found by certain criteria
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program 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.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Exception
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @author    Mikael Nordfeldth <mmn@hethane.se>
+ * @copyright 2013 Free Software Foundation, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
+ * @link      http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+
+/**
+ * Class for an exception when a local user is not found by certain criteria
+ *
+ * @category Exception
+ * @package  StatusNet
+ * @author   Evan Prodromou <evan@status.net>
+ * @author   Mikael Nordfeldth <mmn@hethane.se>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
+ * @link     http://status.net/
+ */
+
+class NoSuchUserException extends ServerException
+{
+    public $data = array();
+
+    /**
+     * constructor
+     *
+     * @param array $data user search criteria
+     */
+
+    public function __construct(array $data)
+    {
+        // filter on unique keys for local users
+        foreach(array('id', 'email', 'nickname') as $key) {
+            if (isset($data[$key]) && !empty($data[$key])) {
+                $this->data[$key] = $data[$key];
+            }
+        }
+
+        // Here we could log the failed lookup
+
+        parent::__construct(_('No such user found.'));
+    }
+}