IMPORTANT CHANGES:

After alpha release 2:

The "abook_delete()" API call has been renamed to "abook_deleteent()" to
clarify its function.  There is now a new "abook_delete()" function which
takes different parameters.

After alpha release 3:

This API now requires the AUTHENTICATE patches and c-client version
3.3.  See the REQUIREMENTS section of the README.
