[FR] suppert for .webp format

[KronosTheLate]

Google's webp format is making grand promises:

WebP is a raster graphics file format developed by Google intended as a replacement for JPEG, PNG, and GIF file formats. It supports both lossy and lossless compression,[8] as well as animation and alpha transparency.

I was unable to find a julia package for saving/loading webp files. Could we support that here?

[KronosTheLate]

Relevant resource: https://developers.google.com/speed/webp/

[stemann]

https://github.com/stemann/WebP.jl

ImageIO PR is queued: JuliaIO/ImageIO.jl#67

[KronosTheLate]

Amazing!! Thank you, that is really nice :D