The subject of pizza is always on the minds of New Haveners, whether it’s deciding what kind to order and where to order it from or what makes the perfect pie and slice. On Friday night, those pies and slices were unveiled as the theme of a world premiere art exhibit at District NHV.“New Haven Pizza Club: Discover the Art of Pizza” showcased the four-year-long odyssey of artist Michal Pollack to commemorate everyone’s favorite meal as a contemporary symbol representing a local legacy.