Added org/postgresql/DriverClass.java to the list of files removed by make clean (it's dynamically built)

Added org/postgresql/DriverClass.java to the list of files removed by make clean (it's dynamically built)
Fixed Statement, so that the update count is valid when an SQL DELETE operation is done.
While fixing the update count, made it easier to get the OID of the last insert as well. Example is in example/basic.java