Fix: Remove string literals relating to Property XML names from MultiColumnList class.
Fix: Remove string literals relating to Property XML names from MultiColumnList class.

ruleless/CEGUI,OpenTechEngine/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI