Cache animated tile speed, use btree map for animated tiles

src/newgrf_station.cpp

@@ -924,6 +924,14 @@ void AnimateStationTile(TileIndex tile)
 	StationAnimationBase::AnimateTile(ss, BaseStation::GetByTile(tile), tile, HasBit(ss->flags, SSF_CB141_RANDOM_BITS));
 }
 
+uint8 GetStationTileAnimationSpeed(TileIndex tile)
+{
+	const StationSpec *ss = GetStationSpec(tile);
+	if (ss == nullptr) return 0;
+
+	return StationAnimationBase::GetAnimationSpeed(ss);
+}
+
 void TriggerStationAnimation(BaseStation *st, TileIndex tile, StationAnimationTrigger trigger, CargoID cargo_type)
 {
 	/* List of coverage areas for each animation trigger */