Merge branch '18.0' of git@github.com:Dolibarr/dolibarr.git into 18.0

htdocs/core/class/commonobject.class.php

@@ -167,6 +167,10 @@ abstract class CommonObject
 	 * @var CommonObject To store a cloned copy of object before to edit it and keep track of old properties
 	 */
 	public $oldcopy;
+	/**
+	 * @var CommonObject To store old value of a modified ref
+	 */
+	public $oldref;
 
 	/**
 	 * @var string		Column name of the ref field.