created plugin custer, and removed shortcodes change_id and user_infos from cipf plugin

plugins/custer/custer_class.php

@@ -0,0 +1,48 @@
+<?php
+namespace CUSTER;
+
+/*
+* it means someone outside wp is accessing the file, in this case kill it.
+*/
+if (!defined('ABSPATH')) {
+	die('You can not access this file!');
+}
+
+
+
+
+
+/*
+*
+*/
+class Custer {
+	
+	const USER_INFO_DATE_FORMAT = 'd/m/Y'; // for user_infos.php (date format : https://www.php.net/manual/fr/datetime.format.php)
+	private static $_backup_current_user = null;
+
+
+	/*
+	* setter and getter for current user backup
+	*
+	*/
+	public static function set_current_user_backup() {
+		if (self::$_backup_current_user !== null)
+			return;
+		self::$_backup_current_user = get_current_user_id();
+	}
+	public static function get_current_user_backup() {
+		return self::$_backup_current_user;
+	}
+	public static function reset_current_user_backup() {
+		$backup_user = self::$_backup_current_user;
+		self::$_backup_current_user = null;
+		return $backup_user;
+	}
+
+
+}
+
+
+
+
+?>