DB_DEGREE_2, DB_DIRTY_READ

The names of two isolation-level flags changed in the Berkeley DB 4.4 release. The DB_DEGREE_2 flag was renamed to DB_READ_COMMITTED, and the DB_DIRTY_READ flag was renamed to DB_READ_UNCOMMITTED, to match ANSI standard names for isolation levels. The historic flag names continue to work in this release, but may be removed from future releases.