In an extraordinary outpouring of support for a priest accused of sexual abuse, hundreds gathered at St. Brendan’s Parish in Dorchester Thursday evening to attend a Mass for the Rev. James H. Lane, the parish’s beloved longtime pastor. It was a quiet service until the end, when one of Lane’s oldest friends, Harry Uhlman, rose to speak. “I don’t care what anybody says,’’ he said. “Father Lane never abused a child.’’ The packed church shot to its feet, and crashing applause filled the sanctuary.