The result of CIRCNetwork::IsUserOnline() will only show clients which
do not have the away state set. This value is not set from the IRC
command AWAY, but a future module could use this behaviour.
Some CIRCNetwork::IsUserAttached() checks are now moved into of
CIRCNetwork::IsUserOnline() checks.
This allows "away" clients to store buffer even if KeepBuffer is false.