Detecting dead connections

[apparentorder]

When the TCP connection to the IRC server goes away silently (because of network issues, drowned servers, surprise packet filters and so on), JustIRC does not notice this, as it does not send IRC PINGs by itself.

In that case, it depends on TCP Keepalive to detect a dead connection. Unfortunately, if enabled at all, the default value is two hours. So in case of a dead connection, JustIRC will just hang for two hours before finally terminating.

In my specific case the timeout issues are related to some weird IPv6 setup problems (don't ask), so an option to force using IPv4 only would be appreciated.

[gkbrk]

We should probably start sending PING packets ourselves.