Real-Time Multiple Lidar Merge

This is a module that collects multiple Lidar point cloud pieces installed on a vehicle and merges them into one large point cloud. The module estimates the rotational speed of the lidars in real-time to minimize frame overlap and achieve nearly constant output frequency, even with input delays in some of the lidars. If the vehicle's pose information is available, it can correct distortions caused by the vehicle movement speed. For performance, input lidars are processed in separate threads, but the real-time merging results are written to the same memory space. To minimize contention for shared memory, the buffer is divided into small segments and distributed to Lidar processing threads as needed, and implemented as lock-free.