ADDREGEXP [duration] <regexp> <reason>
[ADMIN] Adds regular expression match for connecting clients
  <duration>: Duration regexp lasts (not duration of kline)
  <regexp>  : The regular expression pattern to add
  <reason>  : Reason for ban

The regular expression takes the form of:
  ^nickname!username@hostname#gecos$

The regular expression must contain all four fields, together with the
'^' and '$' characters.

Note, regular expressions are not the same as the normal '*' and '?' 
wildcard characters and the regular expression cannot contain an actual
space character ' '.  The regular expressions must be in perl form.

When a user connects to the network, their information is compared
against the list of regular expressions and if any matches are found
then a kline is issued on the users hostname.  When a regular expression
is added, all existing users matching the expression will also be klined.

Note, the duration field is the duration for the regular expression
itself, not for how long the kline will last.  The duration of the kline
is controlled by the config file.

For an introduction to regular expressions, see:
  http://docs.ircd-ratbox.org/regexp.shtml
