Improved (De)Serialization Support

I have added support in readfuncs.c to write out Query and PlannedStmt objects
using nodeToString() and then read them back in. We needed this so that we
could use PREPARE and write the arguments to StorePreparedStatement() out to
a file. We are going then read them back into Postgres on a different server
and use EXECUTE.

Most of the changes involved adding new functions that can do the reverse of
all the functions in outfuncs.c. I am still working on getting the
deserialization part to work correctly, but I wanted to ask two basic
questions:

1) Is there any reason why this shouldn't work? I did have to add calls to
fix_opfuncids() in a couple places for some of the Exprs. Can anybody think
of something else that I should watch out for?

2) Would anyone be interested in committing my changes back to CVS? I want to
know before I move my changes over to a CVS checkout of Postgres.

Thanks!
--
Andy Pavlo
pavlo(at)cs(dot)brown(dot)edu