This patch includes the initial changes required to implement
Drupal 6 support. It is based upon the patch originally provided
by tinker in http://drupal.org/node/1082082

 and contains:

- Updated README.txt
- Switch from inventoried items to services. I know both (and
  non-inventory items) need to be supported, but needed to use
  services for my application (donations).
- Initial support for the lookup of parent accounts' ListIDs when
  creating children. Note that the format for such accounts is
  "ancestor:child".

I know there's still lots more to do. Feel free to open bugs
reports against this branch for needs you notice.

Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>