(svn r2921) -Codechange: moved all AI-code to 1 central place (ai/ai.c)

-Fix: removed the ability for the oldAI to cheat (this will criple him somewhat)
-Add: base-code for many improvements to come in the AI-system
-Add: added base-code for multiplayer AIs (DOES NOT WORK YET!)

openttd.h

@@ -215,7 +215,7 @@ typedef struct GameDifficulty {
 	int initial_interest;
 	int vehicle_costs;
 	int competitor_speed;
-	int competitor_intelligence;
+	int competitor_intelligence; // no longer in use
 	int vehicle_breakdowns;
 	int subsidy_multiplier;
 	int construction_cost;