WEBIRC: Don't respect hostname when DNS is disabled

When DNS lookups are disabled, don't set the hostname received by the
WEBIRC command, but use the IP address instead.

Reported by Toni Spets <toni.spets@iki.fi>, thanks!

Closes bug #167.
Implement new configuration option "Network"

The new configuration variable "Network" is used to set the (completely
optional) "network name", to which this instance of the daemon belongs.
When set, this name is used in the ISUPPORT(005) numeric which is sent to
all clients connecting to the server after logging in.

Closes bug #165.
Merge branch 'bug165-005-NETWORK' of git://arthur.barton.de/ngircd-alex

* 'bug165-005-NETWORK' of git://arthur.barton.de/ngircd-alex:
  Implement new configuration option "Network"
Merge branch 'bug167-WebircIPAnoDNS' of git://arthur.barton.de/ngircd-alex

* 'bug167-WebircIPAnoDNS' of git://arthur.barton.de/ngircd-alex:
  WEBIRC: Don't respect hostname when DNS is disabled