[patch] plproxy v2

We have written a FAQ, where are common issues collected, there
are also discussion about design decisions and why concentrating
only to functions is good idea.

http://plproxy.projects.postgresql.org/faq/faq.html

The patch itself is attached, and also made available here:

http://plproxy.projects.postgresql.org/plproxy-v2.diff.gz

Changes since v1:
- dynamic record patch from Lei Yonghua. That makes functions
that require result types specified with AS clause work.
- accepts int2/4/8 from hash function
- removed get_cluster_config()
- draft sgml documentation
- disabled binary I/O by default.

- parser.y: remove use of alloca, define malloc/free to palloc/pfree
- scanner.l: fix crash if palloc() throws exception by reinitializing
flex properly
- make installcheck work
- removed backwards compat code
- use bool instead bitfields to conform to Postgres coding style.

Todo:
- the docs should be more fleshed out
- should regtest moved to src/test/regress?
- make GUC vars for binary i/o and connection_lifetime?

I mentioned that I planned to remove SELECT/CONNECT too.
Now I've thought about it more and it seems to me that its better
to keep them. As they give additional flexibility.

CONNECT - allows to test plproxy without creating plproxy schema.
Good for quick hacks, RPC-s. Main problem is that as soon
user starts to have several environments - dev/test/live -
he will get hurt, but that could be solved by giving suggestions
in docs how to avoid that. Eg. suggest using service= or fake hostnames.

SELECT - main reason to keep it would be to allow calling
different functions, having different argument/result names
or types.

--
marko