[freeciv-ai] AI Use of Explorers

[Ed Earl Ross <edearl@xxxxxxxxxxx>]

After AI explorers have finished exploration and having found nobody 
else on their island, the explorers go to a city and stay there 
forever--never to be used again. A better use of these expended 
explorers is to use them to hasten building additional settlers, in 
cities that produce settlers slower than population increase.