Fixed wrong Topic name for Landmarks (#1171)
Fixed wrong Topic name for Landmarks (#1171)

The expected topic name for the cartographer seems to be landmark not landmarks even tough a list of landmarks is expected.
cartographer-project/cartographer_ros,googlecartographer/cartographer_ros,wohe/cartographer_ros,googlecartographer/cartographer_ros,cartographer-project/cartographer_ros,cartographer-project/cartographer_ros,wohe/cartographer_ros,googlecartographer/cartographer_ros,wohe/cartographer_ros