1) Removed most static variables for thread safety.

1) Removed most static variables for thread safety.
2) Trial implementation of the thread safe driver under
   Windows.
3)  Fix a bug about DSN options setting.
4)  Fix a bug about Driver options setting.
5) Implement SQLProcedureColumns().
6) Changed default numeric precision/scale.
7) Fix some memory leaks in Unicode driver.
8) datetime -> timestamp with time zone since 7.0.
9) Change manually started(using begin) transactions never
   be implicitly committed.