The following patch allow users to configure the Unix domain socket path, using the...

The following patch allow users to configure the Unix domain socket path, using the "Uds" property.
I took some code from the unixODBC PG driver and performed the necessary adjustments.
Please note that unlike unixODBC, I have followed the current convention, which means that:
1) "Uds" is considered only if "Servername" is empty.
2) Default path is "/tmp".
3) The provided path should point the folder that comtains the UDS node.
[Ramon Danieli]