Yiming Zhang

fix: unexpected list reference issue

2

This is a serious bug, `label_to_segs[label].extend(segs)` unexpectedly modifies the list in `object_id_to_segs[object_id]` as `segs` are assigned to both `label_to_segs[label]` and `object_id_to_segs[object_id]` by reference. This results in some segments being assigned...

The allocated CUDA memory was not initialized but was assumed to be all 0, which may cause `CUDA kernel failed: an illegal memory access was encountered`. `cudaMemset` code was added...

Add fp16 support for sample_farthest_points, ball_query and knn

1

add fp16 CUDA supports for [sample_farthest_points](https://github.com/facebookresearch/pytorch3d/blob/055ab3a2e3e611dff66fa82f632e62a315f3b5e7/pytorch3d/ops/sample_farthest_points.py#L18), [ball_query](https://github.com/facebookresearch/pytorch3d/blob/055ab3a2e3e611dff66fa82f632e62a315f3b5e7/pytorch3d/ops/ball_query.py#L55) functions via `AT_DISPATCH_FLOATING_TYPES_AND_HALF` and [knn](https://github.com/facebookresearch/pytorch3d/blob/main/pytorch3d/ops/knn.py)