With its pastel color scheme and historic decor, Shane Confectionery is the sweetest survivor of Philadelphia’s 19th-century retail revolution. In 1863, Samuel Herring—of the then-renowned confectioner Herrings—opened a wholesale business at 110 Market Street. His son, also named Samuel, was busy fighting for the Union in the Civil War, but when he returned in 1865, he took over the shop. With fellow confectioner Daniel S. Dengler, Samuel did a brisk trade in wholesale ingredients, including glucose, dates, nuts, and cocoa. Wholesale was fine and dandy, but the pedestrians of Philadelphia…