Indexam API changes

There's a bunch of mails in the patch queue about the indexam API, so we
need to discuss that.

The first question is: do we want to refactor the bitmap index scan API,
if we don't have any immediate use for it? Namely, since we don't have
anyone actively working on the bitmap index patch nor the git patch.

There was also discussion on adding support for "candidate matches",
mainly for GIT, but GiST could possibly also take advantage of that.

If people think it's worth it, I can fix the bit-rot in the patch and
work on it, but personally I don't think it is.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com