You know you’ve made an impact on the world when they celebrate your birthday 75 years after you’ve gone. About 75 people gathered yesterday to pay tribute to the life and legacy of trailblazing Richmond native Maggie L. Walker in commemoration of her 145th birthday. “She’d be so happy,“ said Walker’s 84-year-old granddaughter, Elizabeth Randolph, reflecting on the songs of praise and words of gratitude that filled the Third Street Bethel AME Church.