Release 4.2: DB->verify

In previous releases, applications calling the DB->verify() method had to explicitly discard the DB handle by calling the DB->close() method. Further, using the DB handle in other ways after calling the DB->verify() method was not prohibited by the documentation, although such use was likely to lead to problems.

For consistency with other Berkeley DB methods, DB->verify() method has been documented in the current release as a DB handle destructor. Applications using the DB handle in any way (including calling the DB->close() method) after calling DB->verify() should be updated to make no further use of any kind of the DB handle after DB->verify() returns.