Updating API for Postgresql 9.1

The currently published source code (link to the right on the download page) is compatible with Postgresql 8.4, but I have just updated it for 9.1.  Only a couple of minor changes were required it seems.  At the moment, it looks like I've got everything running okay in 9.1, but I will probably wait to post that until I've integrated and tested the API for the state subsystems.  If anyone would like the 9.1 update sooner than that (for the class metamodel subsystems only), let me know and I can make it available.