Add support for the FID metric.
🚀 Feature
Add support for the Frechet Inception Distance as a metric, to evaluate generative models (https://arxiv.org/abs/1706.08500)
Motivation
This metric is used in many recent GAN applications to evaluate the perceptual quality of the generated images.
It is therefore a very helpful and important metric to implement.
Alternatives
The inception score could be also used as well, but FID is more acceptable today.