Consider replacing lena.tif with a free image #728
Description
Is your feature request related to a problem? Please describe.
Mathics ships a copy of the Lena test image under mathics/data/ExampleData/lena.tif. Despite being widely used, this image is non-free and its redistribution is problematic, which complicates packaging Mathics for Linux distributions, among other things.
Describe the solution you'd like
Ideally the image would be replaced with a free alternative and the documentation that references it would be adapted.
Describe alternatives you've considered
I discovered this while attempting to package Mathics in Fedora. As stopgap, I can write a shellscript to strip lena.tif from the source tarball, which will unblock packaging, but this solution is suboptimal as the documentation will still reference it, and it requires an additional manual step when updating the package.
Additional context
python-pillow/Pillow#884 and matplotlib/matplotlib#1581 discuss how Pillow and matplotlib addressed the issue and presents a few potential alternatives. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=758442 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=771191 and this mailing list thread have more details on why the image is not freely distributable and also discuss alternatives.