Long before there was a film called The Greatest Showman, Broadway had its own musical version of the life of P.T. Barnum. This show, simply called Barnum, featured a score with music by Cy Coleman (Sweet Charity, City of Angels), lyrics by Michael Stewart (I Love My Wife) and a book by Mark Bramble (42ndStreet). Using the three-ring circus as the conceit for telling Barnum's rise to fame as the King of…