UseServerSidePrepare default

The docs on ODBC configuration options recommend UseServerSidePrepare=1
for server versions 7.4 and above. That's a good recommendation. Given
that "7.4 and above" covers all supported versions of PostreSQL, and
every reasonable version people might want to use a new driver with, how
about we make UseServerSidePrepare=1 the default, so that people don't
need to set it manually?

- Heikki