new GDA Postgres provider

[Vivien Malerba <malerba linuxbox com>]

Hi all!

I've been working on the data types in the postgres provider and now the
following features should work:
* most of the usual postgres data types are taken into account. The unknown
ones are treated as GDA_TypeVarchar. Some other ones will be added soon. The
date/time types are not well formated at the moment.

* the values returned by the server should be OK (if unknown type, it is a
considered a varchar). The function GDA_Recordset_fetch() in gda-stubs.c
gives a good idea of which part of the union in GDA_Value->_u is accessed
depending on GDA_Value->_d if you do not know which part of the union to set.

* the data type mapping has been done so that you get the same GDA
data types if you use the postgres provider directly or if you use the odbc
provider (with the postgres ODBC driver) to access a postgres DB.


The client libs still need to be modified to render correclty all the data
types (function gda_stringify_value() in gda-clnt/gda-field.c). I can start to
modify it if it is OK with you rodrigo.

If you want to try it out, tell me of any problem you have.

Vivien