Photos now automatically selected from the directory /images/people,
assuming that the image has the same file name as the profile page,
switching md for jpg.

Add anonymous icon for missing profile photos.

Add skeleton profiles for the JS team.

Fix person card heights, add padding between cards.

* People may be assigned to multiple research projects.
* Plugin for advanced filter expressions (see also
  https://github.com/jekyll/jekyll/pull/4478)