Support for newer Postgres / extension packaging

[pvh]

Hi there - I was thinking about basically writing this type and while this code looks crazy stale I'm currently poking at it to get it built against a newer Postgres. Are you interested in pull requests?

[hvisage]

@pvh If @samv is not responding, fork and publish (a pull request would also show others where your repo is to get the updates to test/fork ;)