Infra sharing: Disallow control over other company trains wholly in depots

See: #469

src/infrastructure_func.h

@@ -72,7 +72,7 @@ static inline CommandCost CheckInfraUsageAllowed(VehicleType type, Owner infra_o
  */
 static inline bool IsVehicleControlAllowed(const Vehicle *v, Owner o)
 {
-	return v->owner == o || (v->type == VEH_TRAIN && IsTileOwner(v->tile, o));
+	return v->owner == o || (v->type == VEH_TRAIN && IsTileOwner(v->tile, o) && !v->IsChainInDepot());
 }
 
 /**
@@ -84,7 +84,7 @@ static inline bool IsVehicleControlAllowed(const Vehicle *v, Owner o)
  */
 static inline CommandCost CheckVehicleControlAllowed(const Vehicle *v)
 {
-	if (v->type == VEH_TRAIN && IsTileOwner(v->tile, _current_company)) return CommandCost();
+	if (v->type == VEH_TRAIN && IsTileOwner(v->tile, _current_company) && !v->IsChainInDepot()) return CommandCost();
 	return CheckOwnership(v->owner);
 }