Provide a way to perform PNG optimization on export, similar to what tinypng, optipng or pngcrush are doing

Submitted by Thomas Hotz

Description

This is a bug from https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/1198562.

From the report:

Hi, about large PNG files w/o smart lossy compression techniques. GIMP creates very large PNGs compared to TinyPNG (http://tinypng.org/) with smart lossy compression techniques. I was able to reduce file size from 161.3 KB to 48.4 KB, that's -70% file size reduction! I hope this can be used in GIMP by default in the near future.

See attachment: large-ubuntu-sami-suomi-2013-07-07.png and ubuntu-sami-suomi-2013-07-07.png

Version: 2.8.4