The cast of Mamma Mia! in action.(Photo by Carol Rosegg)By Hap ErsteinThat much-maligned theater stepchild, the jukebox musical, is built from used parts, involving the meticulous selection and insertion of existing songs into a story line to make a cohesive whole.But if a careless mess like Mamma Mia! can run for years on Broadway, generate road companies all over the globe as … [Read more...]