By Denny Dyroff, Entertainment Editor, The Times  Waitress Pie was celebrated in the middle of March with “π Day (Pi Day)” on March 14. Pie will also be celebrated in Philadelphia this week when the Kimmel Cultural Campus presents the popular musical “Waitress” at the Academy of Music (Broad and Locust streets, Philadelphia, www.kimmelculturalcampus.org) from March 29-April 3. Never underestimate...