use ADL and explicit instantiation for map matching

include/engine/routing_algorithms/map_matching.hpp

@@ -30,8 +30,9 @@ SubMatchingList mapMatching(SearchEngineData<Algorithm> &engine_working_data,
                             const std::vector<unsigned> &trace_timestamps,
                             const std::vector<boost::optional<double>> &trace_gps_precision,
                             const bool allow_splitting);
-}
-}
-}
+
+} // namespace routing_algorithms
+} // namespace engine
+} // namespace osrm
 
 #endif /* MAP_MATCHING_HPP */