Facebook application

We should let users associate their Identi.ca accounts with their Facebook accounts. This would mean:

0. Define a link between an account on Facebook and an account on Identi.ca.
1. Optionally add a widget to their Facebook profile showing their recent notices on Identica. (default: yes)
2. Optionally update their status on Facebook from their notices on Identi.ca. (default: yes)
3. Optionally don't update Facebook status if the notice is a reply. (default: don't update)
4. Invite friends on Facebook to use Identica. If friends accept the invitation, the user would automatically be subscribed to them. (On demand)
5. Optionally keep friends on Identi.ca synched with Facebook friends. As you get new friends on Facebook, if they have an account on Identi.ca, we automatically subscribe you to them. (default: yes)
6. Optionally keep friends on Facebook synched with Identi.ca friends. (default: no)
7. Optionally post a new notice on Identica when your Facebook status changes (default: no -- gotta be careful of loops).
8. All the text should be i18n-able.
9. All the look-and-feel should be theme-able (by site).
10. It should work for other Laconica instances, too.