Patch: Autologin/out and more

Please review attached patch and see if it can be incorporated to the official version.

The following login/out features are new:
- Auto log in if the user is logged in to Facebook and already has a linked account.
- Auto log out if the user logs out from Facebook.
Note: Auto log out logs the user out only on the second Drupal page load after having logged out from Fb. This seems to be a limitiation in the Fb PHP API - the Fb Run Around demo application behaves the same way.

The following feature is also new:
- Define an admin setting to silently import user data when choosing the 1click registration (without asking the user for approval).

In addition, I have included the patch the feature from the earlier feature request to call a hook when inserting profile data. I have also added Facebook first and last name in addition the full name. (This would need to incorporated for an update in the install file too).

Bugfix:
- Log the user out from Facebook only if the currently logged in Drupal user has a Facebook account linked.

The patch is against the 5.x dev release.