Feature Request: Provide a way to disable animated gif processing

[hardyoyo]

For sites that host a large number of animated GIFs as resources, batch loading more than a 100 animated GIFs at at time can cause downtime, as the image optimization processes conducted by Manifold fan out and consume both CPU and RAM on a server. Since GIF images can be pre-optimized by the user, it would be handy to have a flag or environment variable to disable further processing/optimization of GIF images, so that a site can avoid downtime, and still host the resources it needs to host.