News Commentator H. V. Kaltenborn and his wife Olga, photographed in the garden of their Manhattan home, have played tennis together all over the world since 1910. This winter the Kaltenborns have been playing indoors at the River Club. In summer they play at their country home in Stony Brook, L.I. Now 77, H. V.'s ambition is to top the late King of Sweden, who played until he was 88. "Most people," says Kaltenborn, "think tennis just a younger people's game. When people quit at 50, they stop enjoying one of the finest games in the world."