New location for Antik and GSLL git repositories

The git repositories and development pages for Antik and GSLL are now on gitlab.common-lisp.net under the "antik" group: https://gitlab.common-lisp.net/groups/antik If you clone/pull directly from the git repositories, update the URL as the old locations have been deleted. Those who get the projects exclusively from Quicklisp are unaffected by this change. Liam