fmtId() and pg_dump

The attached patch implements the scheme outlined on -hackers a little
while ago for reducing the usage of fmtId() in pg_dump. This is just
a "proof of concept" -- I added a simple wrapper over
appendPQExpBuffer() that takes an extra formatting sequence. The
implementation is pretty trivial -- the assumption is made that

(a) all printf-like formatting sequences consist of a '%' followed
by a single character

(b) any occurance of a '%' is a part of a formatting string

I've converted a few of the places where fmtId() is used over to the new
syntax. The reason I'm posting the patch is to get some feedback:
is this a better method can just calling fmtId()?

If so, I'll add some comments, convert all the code to use the wrapper
as necessary, and think up a better name for the wrapper function.

Cheers,

Neil

--
Neil Conway <neilconway(at)rogers(dot)com>
PGP Key ID: DB3C29FC