#4 New /who selection flag

[Joe Hansche]

This patch is intended for use with the "delayed join"
patch. /names -D #channel will work fine for getting
the nicks that are hidden by the +d/D chanmode, but
other than using that /names reply in conjunction with
a /userhost for each of those nicks, there is no way to
gather the hosts of those nicks, or any other
information in a /who. This patch adds a 'd' selection
flag, to indicate that the reply should include those
users that are hidden by +d/D. It's use is as follows:

/who #channel d
/who #channel dx%nhi
etc

[Joe Hansche]

WHO flag addition, for the delayed_join patch.