It was not handling the URLs properly/parsing of the URLs, as well as missing ->owner.
Would really appreciate this being quickly patched as I need it to be working for a project.
This replaces the existing updateItems() + extension hook in favour of consistency with the register_dataobject() interface.
Note that this will likely be superseded by something to do with the Config API in the future.
Misc upgrade of module code so that site map.xml provides a index site map file based on the standards. Moved configuration vars to the Config API.
Considering how large a change this is, I've branched a 1.0 release off in github.