= New Features

* The tree and rcte_tree plugins now support composite keys.

* An error_sql Database extension has been added.  This extension
  adds the DatabaseError#sql method, which should return the
  database query that caused the error.  This is useful for
  drivers that don't include the SQL used as part of the error
  message.

= Other Improvements

* Empty blobs are now literalized correctly on MySQL.

* Empty arrays are now literalized correctly on PostgreSQL <8.4.

* In the pagination extension, Dataset#page_count is now 1 even if
  the dataset is empty.  This fixes issues with last_page? and
  page_range returning bad values for empty datasets.

* In the pagination extension, calling Dataset#each_page without a
  block now returns an Enumerator.

* Dataset#qualify and Sequel.delay now work together, qualifying
  the object returned by the delayed evaluation.

* Migrator.migrator_class is now a public method.

* The PostgreSQL citext type is now recognized as a string.

* Another disconnect error is now recognized in the jdbc/as400
  adapter.

* Guides about using and creating Sequel extensions and model
  plugins have been added.

= Backwards Compatibility

* If you were expecting Dataset#page_count on a empty paginated
  dataset to return 0, you need to update your code.
