using the repo with Ubuntu20 and C++17

[niuwengang]

When using this repo with ubuntu20 and c++17,you need to add and modify some code.

1. data_io.cpp

#add
 #include <boost/thread/thread.hpp>  

2. CMakeLists.txt

#add
find_package(Boost REQUIRED COMPONENTS
serialization timer thread chrono)
#modified
SET(CMAKE_CXX_FLAGS "-O3 -std=c++17 -w -fopenmp -pthread ")
SET(CMAKE_C_FLAGS "-O3 -std=c++17 -fopenmp -pthread ")
SET(DEP_LIBS ${DEP_LIBS} ${OpenCV_LIBS} ${PCL_LIBRARIES} ${libLAS_LIBRARIES}  ${Boost_INCLUDE_DIRS})