Optimize and Integrate Standalone Tracking Library (SixTrackLib)

The project targets optimizing the data structures and source code of a standalone tracking library, SixTrackLib, written in C. The aim is to restructure the code such that it enables auto vectorization in GCC and CLang for CPU. In addition, the code should also be amenable to execution on the GPU, having low register pressure. The idea is to keep the code structure relatively simple and maximize the shared code between CPU and GPU. The optimized SixTrackLib module will be integrated into the legacy SixTrack code.