At the sad news of Ian Falconer’s death at 63 this week, I thought of Venice, though I have never been there. What came to mind was not the city itself, but the many gelatos that Falconer’s spunky picture-book heroine Olivia eats before and after her family’s travails on their sinking gondola while in the Italian city. When my sons were in preschool, they never tired of counting up the outrageous number of gelatos that Olivia’s parents hand out to their little piglets in Falconer’s wondrous mixed-media scenes in his 2009 book “Olivia Goes to Venice.”