added 2 second uninstall delay, on very fast systems the lnk-file is still used and cannot be removed resulting in an uninstall error

Author: Hirogen

src/setup/ExtraFunctions.iss

@@ -57,6 +57,7 @@ begin
     if (IsUpgrade()) then
     begin
       UnInstallOldVersion();
+      Sleep(2000); //wait two seconds here so uninstaller releases lnk files
     end;
   end;
 end;