Expose autologout initialization API. Allow for unconditional drupal_alter() of autologout_timeout

I'd like to propose a patch that would:
- move the majority of autologout initialization code into a separate function called autologout_initialize(). That would allow other modules to initialize autologout on their own
- allow for drupal_alter()ing of autologout_timeout even for anonymous users

The use case I'm aiming to cover here is of external authentication and/or authorization - a user has to go through an external login form or similar in order to even gain access to the website as an anonymous user.