latest revision of the postgres provider

[Vivien Malerba <malerba linuxbox com>]

Hi All!

I've commited the (I hope) stable version of the postgres provider with the
most usual data types mapped, and also the client lib with a very small
modification to display date/time correctly.

Next step is to see about the schema stuff, and I will give you my opinion on
the problem.

Cheers
Vivien