ATLANTA—Former Georgia Republican senator Johnny Isakson died on Sunday. He was 76. Isakson died in his sleep before dawn at his home in Atlanta, his son John Isakson told The Associated Press. He said that although his father had Parkinson’s disease, the cause of death was not immediately apparent. “He was a great man and I will miss him,” John Isakson said. Johnny Isakson, whose real estate business made him a millionaire, spent more than four decades in Georgia political life. In the Senate, he was the architect of a popular tax credit for first-time home buyers that he said would help invigorate the struggling housing market. As chairman of the Senate Veterans Affairs Committee, he worked to expand programs offering more private health care choices for veterans. Isakson’s famous motto was, “There are two types of people in this world: friends and future friends.” That approach made him exceedingly …