* Enable to convert Batch data back to torch. * Add torch converter to collector. * Fix * Move to_numpy/to_torch convert in dedicated utils.py. * Use to_numpy/to_torch to convert arrays. * fix lint * fix * Add unit test to check Batch from/to numpy. * Fix Batch over Batch. Co-authored-by: Alexis Duburcq <alexis.duburcq@wandercraft.eu>