Summary: Add a new implicit module Integral Position Encoding based on [MIP-NeRF](https://arxiv.org/abs/2103.13415).
Reviewed By: shapovalov
Differential Revision: D46352730
fbshipit-source-id: c6a56134c975d80052b3a11f5e92fd7d95cbff1e
Summary: Update all FB license strings to the new format.
Reviewed By: patricklabatut
Differential Revision: D33403538
fbshipit-source-id: 97a4596c5c888f3c54f44456dc07e718a387a02c
Summary:
Moved `HarmonicEmbedding` function in core PyTorch3D.
In the next diff will update the NeRF project.
Reviewed By: bottler
Differential Revision: D32833808
fbshipit-source-id: 0a12ccd1627c0ce024463c796544c91eb8d4d122