Small modifications and examples to experiment with social net functions.
popco.lisp: init-pop now merges group memberships into folks
variables.lisp: *all-social-net-groups* now defaults to nil rather than (folks)
crime3.lisp: modified crime-talker person-creation functions to take optional social net group, etc. arguments
crime3socnet1.lisp: An initial experiment with social net functions. Doesn't work yet.