fixed a casting of map into multimap
fixed a casting of map into multimap

willdzeng/rtabmap_ros,introlab/rtabmap_ros,introlab/rtabmap_ros,willdzeng/rtabmap_ros,Notou/rtabmap_ros,introlab/rtabmap_ros,willdzeng/rtabmap_ros,introlab/rtabmap_ros,jian-li/rtabmap_ros,jian-li/rtabmap_ros,Notou/rtabmap_ros,Notou/rtabmap_ros,jian-li/rtabmap_ros