deleted some obsolete code

by aangel, Dave Cohen: stop using authmap table, use new table fb_user instead, for mapping local accounts to facebook ids.

Expand fieldsets by default when creating new application.

minor tweaks.

Change the fb_cb url rewrite syntax.  Now use apikey instead of label.  This helps simplify fb_settings.inc.
multiple simplifications (fixes, lets hope) to fb_settings.inc.
fb_session.inc no longer needed (at least for time being).
more sanity checks and output in fb_devel.module

numerous changes, especially to session management and url rewriting. performance improvements and code simplification.

Added checks for whether page is connect.
changed global variable name.
added devel check to catch bad URLs.