Re: Amcheck verification of GiST and GIN

Here's a polished version of the patches. If you have any
comments/objections, please speak now. I don't plan to push 0006 (the
stress test), of course.

Changes I did:

1) update / write proper commit messages, hopefully explaining the
purpose of each patch well enough

2) update the lists of reviewers/authors (would appreciate someone
checking - it's hard to keep track for a thread that runs for years, and
it may not be quite clear what qualifies as a review)

3) squash the fix patch into the right patch, moved the README fix to be
the first patch (doesn't really matter)

4) minor cleanups in the main patches (0002 and 0003), mostly adding the
structs to typedefs.list and tweaking a couple comments

5) I've adjusted names of the memory contexts, because having both with
"amcheck context" seemed confusing, especially as it's in caller-callee
functions. So now it's

- amcheck consistency check context
- posting tree check context

regards

--
Tomas Vondra