#1425 fix: convert mailman links to lists.fsfe.org

find . -iname '*.xml'  -exec perl -pi -e 's/http(s)?:\/\/mail(man)?\.fsfe(urope)?\.org\//https:\/\/lists\.fsfe\.org\//g' {} \;
find . -iname '*.xhtml'  -exec perl -pi -e 's/http(s)?:\/\/mail(man)?\.fsfe(urope)?\.org\//https:\/\/lists\.fsfe\.org\//g' {} \;

Converts all previous `mail.fsfeurope.org` and `mailman.fsfeurope.org` links to the new `https://lists.fsfe.org` domain. This actually solves a lot of broken links. Note that this changes both links and text. Executed commands: ``` find . -iname '*.xml' -exec perl -pi -e 's/http(s)?:\/\/mail(man)?\.fsfe(urope)?\.org\//https:\/\/lists\.fsfe\.org\//g' {} \; find . -iname '*.xhtml' -exec perl -pi -e 's/http(s)?:\/\/mail(man)?\.fsfe(urope)?\.org\//https:\/\/lists\.fsfe\.org\//g' {} \; ``` I've tested some links to verify that the replacement worked, but not all.