Say hello to a channel filter module for identified clients 

The channel filter module maintains client specific channel lists for
identified clients. A typical use case is to have a subset of channels
visible for a mobile client.

The module detects identified clients automatically, and starts
maintaining client specific lists of channels. When an identified
client connects ZNC first time, all channels are joined. The list of
channels is automatically updated when the identified client joins and
parts channels. Next time the identified client connects, it joins the
channels it had visible from the last session.
Ugly :(
This doesn't really belong here.
There can be a function in CUtil, but tags should be passed outside the message