QueryWindow: fix underscore bug

Elwig/Windows/QueryWindow.xaml.cs

@@ -44,7 +44,7 @@ namespace Elwig.Windows {
             for (int i = 0; i < header.Count; i++) {
                 var h = header[i];
                 DataList.Columns.Add(new DataGridTextColumn {
-                    Header = h.ColumnName,
+                    Header = h.ColumnName.Replace("_", "__"),
                     Binding = new Binding($"[{i}]"),
                     CellStyle = (h.DataTypeName == "INTEGER" || h.DataTypeName == "REAL") ? styleRight : null,
                 });