#PPF_Registration Using PPF to achieve point cloud registration.

test environment： pcl 1.12.1 vs 2019 cmake 3.15.2

Notice: 1.We need to manually st the boost path when we camke.

example: E:/PCL 1.12.1/3rdParty/Boost/lib/cmake/Boost-1.78.0

2.Modify the floor function on line 80-81 of the PCL file (pcl-1.12\pcl\registration\impl\ppf_registration.hpp)：

const auto aux_size = static_caststd::size_t(std::ceil(2 * M_PI / search_method_->getAngleDiscretizationStep()));