WGAN-GP loss: averaging penalties or not?

[remicres]

Hi @akanimax

First of all many thanks for this amazing contribution.

In the paper, it is stated we modified the gradient penalty to be the average of the penalties over each input.
I didn't see any of that in the original MSG-GAN tensorflow implementation, neither in the BMSG-GAN implementation: it seems rather like only the gradient penalty of the higher resolution image is used.

Did I miss something, or is it a slight variation between the paper and the implementation?

Cheers

edit: related to #35