message: Add a c'tor to create a LandmarkMapper from given mappings
diff: @@ -97,6 +97,14 @@ public:
  }
  };
  + /**
  + * @brief Constructs a new landmark mapper from a set of existing mappings.
  + *
  + * @param[in] mappings A set of landmark mappings.
  + */
  + LandmarkMapper(const std::unordered_map<std::string, std::string>& mappings) : landmark_mappings(mappings)
  + {};
  +
  /**
  * @brief Converts the given landmark name to the mapped name.
  *
  