setup.py的作用：
将指定模块路径添加到pythonpath中
eg:
kalibr/aslam_incremental_calibration/incremental_calibration_python/setup.py
将package "incremental_calibration"所在路径下的src目录添加到pythonpath中
/persist/chengde/workspace/vio_calib_ws/vio-calib-kalibr_ws/src/vio-calib-kalibr/aslam_incremental_calibration/incremental_calibration_python
~/alsam_backend_python/setup.py
