ChangeLog: Drop this optional file
Users who need a history can get it from the Git repository, and the
file is optional since at least 2006 [1].
[1]: https://gitweb.gentoo.org/proj/pms.git/commit/?id=
81f522241733c87bcfca90b554082a2d0782cd8f
dev-util/update-copyright: update to python3 branch.
Update URLs from einstein to tremily.
Add dev-util/update-copyright package.