The JJA mourns New Orleans’ style by celebrating Francis Davis, our esteemed friend — an author, columnist, editor, poll-meister and inquisitive, insightful thinker about jazz and other dynamic arts, who died April 14 at age 78 in his Philadelphia home. “He died in his sleep Monday morning after several years with emphysema and Parkinsons,” his wife Terry Gross wrote in an email, and posted in a fuller obituary, “but his writing will endure.” Francis was cremated. His friends are invited to join an online memorial service to be held Friday,…