* Finish the man pages.

* Create a user's guide or tutorial.

* Create a generic "get preferred" function that accepts a type a
parameter.  This function can then be used to retrieve the preferred
EMAIL, TEL, ADR, LABEL, and possibly URL.

* Have the type name, param name, and param values all stuffed into
the vc_component as lowercase-only values.  This will simplify the
searching and comparison of these values and eliminate the need for
strcasecmp in a lot of places.
