Bump config file version number to 18

This because of addition of DetailFontSize property to Prefs:Display
section of per-user config file.

Author: delphidabbler

Src/FirstRun.UConfigFile.pas

@@ -3,7 +3,7 @@
  * v. 2.0. If a copy of the MPL was not distributed with this file, You can
  * obtain one at https://mozilla.org/MPL/2.0/
  *
- * Copyright (C) 2007-2021, Peter Johnson (gravatar.com/delphidabbler).
+ * Copyright (C) 2007-2022, Peter Johnson (gravatar.com/delphidabbler).
  *
  * Implements class that manages the updating of older config files to the
  * current format.
@@ -82,7 +82,7 @@   TUserConfigFileUpdater = class(TConfigFileUpdater)
   strict private
     const
       ///  <summary>Current user config file version.</summary>
-      FileVersion = 17;
+      FileVersion = 18;
   strict protected
     ///  <summary>Returns current user config file version.</summary>
     class function GetFileVersion: Integer; override;