The bitmap and image handling interfaces have changed within NetSurf
and the webp image handling has not been fixed up appropriately to
cope.
After discussion with the other developers it has been decided that
the webp support is not worth the necessary development effort to
rewrite and maintain.
The webp format is not in wide usage and Mozilla, Microsoft and Apple
have not adopted it. This means the removal will not adversely impact
NetSurf.
Resolves:2310