Virtual domain support for Qmail-LDAP

This patch implements virtual domain support in auth_* for Qmail-LDAP.

It has some docs, here is just a brief summary:

• you can define LDAP DN for a named virtual domain (usernames like joe@domain.com)
  
• you can define LDAP DN for different server IP addresses (IP-based virtual domains)

You can download the patch here.

The original idea was to port John Morrissey's auto-basedn and virtualpop patches (http://horde.net/~jwm/software/qmail/.) to the newer releases of qmail-ldap, but it turned to be a quite different implementation.

The patch should apply cleanly to the 20060201 release of Qmail-LDAP.

Please report bugs or problems to me.

Last modified: 08 February 2006.