Show the user-agent of visitors to admins in the Who's Online List

[Kolya]

Basically what the "Grouped Who's Online List" mod did. But that mod is long obsolete, mainly because it involved its own spiders list.

As in my support request (How to notice new spiders) I am still somewhat surprised that with all the elaborate spiders management available in SMF 2.0 RC4, there is still no way to identify a new spider, whose user-agent has not been entered into SMF's Search Engines menu yet.
How are admins supposed to do that if they cannot see the user-agents of visitors?