Fix https://github.com/julianhyde/optiq/pull/191, "Rotate time/date/timestamp vals to local timezone".

Following the JDBC specifications, rotate
java.sql.(Time,Date,Timestamp) to be zeroed-out in the local
timezone. Interpret incoming java.sql.(Time,Date,Timestamp) from
external JDBC drivers as being in the local timezone.

ResultSet#getString(int) still returns timestamps formatted
for GMT.