President Leopold Sedar Senghor, 74, of Senegal steps down today after 20 years in office and is replaced by Mr. Abdou Diouf, who has been his Prime Minister for the past 10 years. It was essentially Senghors international stature as intellectual and world-renowned poet that put his poor and arid country on the map. Now by retiring to smooth the succession and in going against current African trends by recently setting up a functioning multi party democracy, Senghor has displayed an independence and foresight rare in the continent.