Frontend/Backend protocol 3.0

Hello people,

I've taken a few days to hack in support for the frontend/backend
protocol v3.0 (which first appeared in PostgreSQL 7.4).  My main
motivator was to get at the SQLSTATE codes which backends >= 7.4 return
with every error message.

What's done now:
  -read the new message length field from all server responses
  -Parse new-style error/notice blocks
  -return correct SQLSTATE from backend to ODBC callers (connection and
result level)
  -added #ifdef so the driver compiles against newer iODBC headers

What I intend to finish this week:
  -upgrade the function call API to new protocol

What needs doing that I can't/won't finish soon:
  -upgrade Windows configuration GUI to add new "7.4" protocol option
  -take advantage of the new transaction status byte in 'Z' messages (my
patch just ignores them)
  -rework prepared statement stuff to use the new protocol features (I
haven't looked at this stuff at all, but the old code works on the new
protocol--it could be faster, that's all)

If there is any interest in this patch, I will post it to the list, or
email it to individuals.

Regards,

-Jonathan Fuerth