PostgreSQL 8.3 related fixes - Changed SQL function method type so that a cast is not needed (fixes #111). - Wrote a preliminary finalizer for PGTSNotifier. - PG 8.3 seems to be more strict with notification names. In particular, full stop won't be allowed in the middle of a name. This is a problem, since we use schema qualified names which are the same as tables' names. For now, a warning message shall suffice, but notification names should probably be changed somehow.