[AD] Yet another EMD implementation for dense point clouds

[Colin97]

If you are looking for EMD of dense point clouds (with over 10,000 points) and large batch size, please check our implementation: https://github.com/Colin97/MSN-Point-Cloud-Completion

[anguyen216]

@Colin97 Do you have more instruction on how to incorporating your implementation in optas' code for latent_3d_points? I'm having issues with compiling the loss functions implemented by optas