By Chris Leadbeater Fit for an emperor, Versailles is a French palatial wonder and beautiful in springtimeThe woozy taste of a fine Bordeaux; the clink of a coffee cup in a Lyon bistro; the sight of Mont Blanc peeping above the slopes of Courchevel; the view of Paris from below the Sacr� Coeur: you never need to think hard to find a reason to visit France.But spring is an especially pleasant time