PARIS — Eighteen months ago, John Galliano showed his last Artisanal collection for Maison Margiela. It was an event that has already passed into fashion legend, so it casts a long shadow, and there aren’t many people I can think of with the imagination, the spirit, the iconoclasm to confront such an overwhelming forerunner. But confrontation has always been what Glenn Martens does best. “The only critique we received when we announced that my first collection for Margiela would be…

