inbound_next_nick() should not pick global 3rd nick if using server settings only
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Certain networks are a bit more professional, while other networks are less professional or more casual, and you generally don't want to leak one into the other.
The patch for this is trivial, pick a randomized nickname (while taking care to avoid overruns) if nick count is greater than 2 and there is no associated server, or the server is not using global settings.
(this bug affects r1525)