GitLab

Summary:
Allow Pointclouds objects and heterogenous data to be provided for Chamfer loss. Remove "none" as an option for point_reduction because it doesn't make sense and in the current implementation is effectively the same as "sum".

Possible improvement: create specialised operations for sum and cosine_similarity of padded tensors, to avoid having to create masks. sum would be useful elsewhere.

Reviewed By: gkioxari

Differential Revision: D20816301

fbshipit-source-id: 0f32073210225d157c029d80de450eecdb64f4d2