ListClients: add identifier column
Update Csocket to b5185dc

> Fix IsConnected() to return false when Disconnected() gets called
Replace CIRCNetwork::FindClient() with FindClients()

FindClient() is not enough, because there are no restrictions to used
identifiers. They don't necessarily need to be unique, and the same
identified client might re-connect meanwhile a ghost connection is
still hanging there.
Merge pull request #752 from jpnurmi/findclients

Replace CIRCNetwork::FindClient() with FindClients()
Merge pull request #751 from jpnurmi/csocket

Update Csocket to b5185dc
Merge pull request #753 from jpnurmi/listclients

ListClients: add identifier column
Add CClient::IsReady()

Tells whether the client is "ready" ie. has received MOTD & buffers.
This is essential information for such modules that want to filter
the initial buffer playback (eg. client specific buffers - #343),
but let buffer playback through when re-attaching a channel.