[Live-demo] compressing images with pngquant

[Johan Van de Wauw]

Hi all,

I've been experimenting with pngquant [1] to reduce the size of our
png images in the documentation. This implements a lossy compression
method, but all images I tried came out just fine.
In total, we could save about 36Mb by using this compression on all
files. I believe this is significant enough to do the change for most
files, especially since they are accessed also over the web by people
reading the quickstart.

I prepared a branch which contains the compressed images at:
https://github.com/johanvdw/OSGeoLive-doc/tree/compresspng
I made a single commit per image, so if we merge we can still roll
back specific images easily.
In fact, on github, you can watch the images side by side or as a slide over.

I suggest we discuss whether or not we merge this branch during the
meeting tonight.

Kind Regards,
Johan

[1] https://pngquant.org/