Make derecognized status more obvious

[adehnert]

It's been pointed out that ​https://asa.mit.edu/groups/795/ could really be more obvious that the group is derecognized. One option is to add a strikethrough to the group name. We could also hide many of the fields for derecognized groups, and force you to click a "yes, I know they're derecognized" button to view them.

[adehnert]

kcr suggests "72-point flashing red message". Which, it's ugly, but it's not like making derecognized groups pretty is a key design consideration...