New configuration opion "MorePrivacy" to "censor" some user information

this patch contains:

  * Fix for Conf_CloakUserToNick to make it conceal user details
  * Adds MorePrivacy-feature

MorePrivacy censors some user information from being reported by the
server. Signon time and idle time is censored. Part and quit messages
are made to look the same. WHOWAS requests are silently dropped. All
of this is useful if one wish to conceal users that access the ngircd
servers from TOR or I2P.