It may be hard to credit in this age of monster McMansions that the “tiny house movement” which began in the hippie `60s, continues to grow. But so say architectural designer and illustrator David Stiles and his wife, Jeanie Stiles, a writer and photographer. Their attractive newest how-to book, Building Small , their 25th, pitches barns, cabins and sheds as weekend and year-round retreats, whether off the grid or on. Would you believe an adorable 8’ X 11’ backyard Tudor or a two-level Japanese