Unfortunately a pretty common spam/annoyance online is putting "spam"
via abusing Unicode symbols - which is used for multilingual support -
in display names. This typically results in an unreadable word jumble in
our UI, which looks bad.
So I decided to put a stop to that by clipping some labels that could be
used for this crap. I didn't cover *everything* yet, but this at least
prevents these idiots from showing up in the completion menu, the room
member list and as authors for messages.
In other messaging applications (e.g. Discord) this is possible through
text modifiers like "from:@user". We don't support that, and I'm not
super keen on implementing yet-another-parsing-thing, so an action in
the user detail dialog should work for now.
Very useful to sift through large rooms but when you only care about a
specific person's messages (maybe your own?)
