Enhanced Documents, handle enhanced steps

Enhanced Documents, delete items
Enhanced Documents button disable/enable
Enhanced Documents, tree view support for insert/delete/copy-paste
Move DisplayText.cs to CSLA
Enhanced Documents adding links (method added in docversion)

PROMS/Volian.Controls.Library/StepPanel.designer.cs

@@ -21,6 +21,7 @@ namespace Volian.Controls.Library
 					EditItem.MyItemInfo.ResetParts();
 					EditItem.MyItemInfo.MyContent.RefreshContentParts();
 				}
+				_LookupEditItems.Clear();
 				components.Dispose();
 			}
 			base.Dispose(disposing);