(svn r2414) - Feature: [newgrf] Implement powered wagons, and the callback that goes with it.

engine.c

@@ -588,6 +588,16 @@ int GetCustomEngineSprite(byte engine, const Vehicle *v, byte direction)
 	return r;
 }
 
+/**
+ * Check if a wagon is currently using a wagon override
+ * @param v The wagon to check
+ * @return true if it is using an override, false otherwise
+ */
+bool UsesWagonOverride(const Vehicle *v) {
+	assert(v->type == VEH_Train);
+	return (GetWagonOverrideSpriteSet(v->engine_type, v->u.rail.first_engine) != NULL);
+}
+
 /**
  * Evaluates a newgrf callback
  * @param callback_info info about which callback to evaluate