preserve session when logging into fbConnect.  So existing user accounts may be mapped to facebook ids

and disable drupal cache when using facebook sessions

Changes to fbConnect session management.  Changing session id when logged in via fb connect.  This prevents the Drupal session from conflicting with the fbconnect session, and ensures user is properly logged out when user logs out of facebook.

Potential security issue here, so enabled only when fb_session_cookieless_iframe variable is set.
Solves a multitude of session state issues, particularly on iframes in safari and ie6 where cookie support is less than acceptable.

Numerous changes to Drupal for Facebook.  Significant updates.  Manual configuration changes required.  http://drupalforfacebook.org/node/1055