When a graphic novel tries to interest young readers in an important topic, it often feels forced. Not so with the exhilarating “March: Book One” (Top Shelf Productions), written by Congressman John Lewis and his aide Andrew Aydin and illustrated by the extraordinarily talented Nate Powell. With powerful words and pictures, it details Lewis’s boyhood in the segregated South, his first meeting with the Rev. Martin Luther King Jr., and his early years in the civil rights movement. Lewis was with King when the civil rights leader delivered his “I Have a Dream” speech at the March on Washington 50 years ago this month. “March,” the first volume in a trilogy, is part of his grand ambition to keep that dream alive.