Volumes data structure.

Summary: Implemented a data structure for volumes.

Reviewed By: gkioxari

Differential Revision: D20342920

fbshipit-source-id: ccc23eaa183ed8a4e9cd7674b4dcf31e8a65c3c6

Author: davnov134

pytorch3d/structures/__init__.py

@@ -3,6 +3,7 @@
 from .meshes import Meshes, join_meshes_as_batch, join_meshes_as_scene
 from .pointclouds import Pointclouds
 from .utils import list_to_packed, list_to_padded, packed_to_list, padded_to_list
+from .volumes import Volumes
 
 
 __all__ = [k for k in globals().keys() if not k.startswith("_")]