Adds max_raytracing_range variable to obstacle layer which is needed for buffered clearing of voxel grid
Moves updater classes (Mark, Clear) into seperated files and also refactoring of them
Adds buffered clearing of voxel grid
Adds parameter to choose between buffered clearing and normal / old style clearing
Adds publisher cleared voxels when using the buffered clearing
Clearing with buffer now keeps track of which cells in the costmap are cleared for future use
TODO: Rename stuff to cached instead of buffered