graphics/gimp is now 3.x

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

I've just updated graphics/gimp to provide the stable version 3.0.4 of
gimp.

I've removed the very outdated gimp-docs packages, and the gimp
plugins that do not support gimp>2. Most of these didn't even have a
homepage, or were last updated more than 5 years ago.

Cheers,
 Thomas