[imp] $autologin in HEAD / access to IMP w/o a horde generated login screen

[Liam Hoekenga]

I'm trying to figure out if I can leverage the HEAD hordeauth / $autologin
stuff.

Basically, we want the user to be let into IMP w/o being presented w/ a "Welcome
to Horde" or "Welcome to Mail" login screen, because we already have all the
information needed to log in.  Horde is using the "auto" authentication
mechanism, and we're setting the horde username to REMOTE_USER:

    $conf['auth']['params'] = array();
    $conf['auth']['params']['username'] = $_SERVER['REMOTE_USER'];

We trust our SSO for authentication, and trust that it's set up the environment
properly, so I felt that despite the huge warnings in horde/lib/Auth/auto.php,
that it would actually work for us.

We're using IMAP + gssapi/krb5, so we don't need users to provide a password to
log in.  The user's kerberos credentials are already on the server (obtained
via our web SSO), and the username is always set to REMOTE_USER.  

I see that there's an $autologin variable, and I'm guessing it has some to do
with the new 'hordeauth' setting in conf/servers.php

I've got hordeauth set to true, and I'm still getting presented w/ a login
screen.  Is this because the "auto" auth mechanism doesn't collect a password,
and IMP thinks it needs a password?

I've got this working in 3.2.2 - made a copy of redirect.php, futzed with it,
and it works fine.  I've done a similar thing w/ previous incarnations of
HEAD.
I'm trying to get it working again w/ HEAD with as little localization as
possible.  

Liam