Belgian designer Pieter Mulier has been appointed as Creative Director of Maison Alaïa. Chief Executive Officer of Alaïa, Myriam Serrano announced the hire on Feb. 5th. The Richemont-owned luxury brand produces both ready-to-wear and haute couture lines.  Alaïa began his couture work in 1965, eventually garnering the nickname "King of Cling" for his svelte, body-hugging…