Improved the column load optimization which was causing object reloads in various circumstances (impact can be important when loading lists with many lines):

1) When changing column settings (menu "Configure this list")
2) When a plugin was systematically reading some data (e.g. Highlighting late tickets requires to read tto/trr/status/start_date!)

SVN:trunk[2925]

core/attributedef.class.inc.php

@@ -210,6 +210,7 @@ abstract class AttributeDefinition
 	public function IsExternalField() {return false;} 
 	public function IsWritable() {return false;} 
 	public function LoadInObject() {return true;}
+	public function AlwaysLoadInTables() {return $this->GetOptional('always_load_in_tables', false);}
 	public function GetValue($oHostObject){return null;} // must return the value if LoadInObject returns false
 	public function IsNullAllowed() {return true;} 
 	public function GetCode() {return $this->m_sCode;}