cartographer源码阅读目标

阅读方法：

1，在2d 的例子上一点点往下简化，能够写一个python版本包最好

2，自己建一个 carto_ros 版本跑起来做对比，做注释

3，最好把 cartographer 也放到 catkin_ws下做方便源码阅读

## scj
# find_package(catkin REQUIRED)
# catkin_package(
# # INCLUDE_DIRS include
# # LIBRARIES test
# # CATKIN_DEPENDS other_catkin_pkg
# # DEPENDS system_lib
# )
# include_directories(
# # include
# # ${catkin_INCLUDE_DIRS}
# )

<export>
<!-- <build_type>cmake</build_type> -->
</export>