Changes to python-ligo-lw will break skymap/util/ilwd.py

Hi Leo,

Apologies if you are already aware of this. We noticed that forthcoming changes to python-ligo-lw (kipp.cannon/python-ligo-lw@a292464f) will break the reading code defined in skymap/util/ilwd.py as IDTypes will be removed. Not sure if it's easily possible to patch this to work with the changes (I ping @tito-canton who has looked at this on our end as well).

Thanks! Ian