= Performance Enhancements

* A mysql2 adapter was added to Sequel.  It offers a large (2-6x)
  performance increase over the standard mysql adapter. In order to
  use it, you need to install mysql2, and change your connection
  strings to use mysql2:// instead of mysql://.
  
* Support for sequel_pg was added to the native postgres adapter,
  when pg is being used as the backend.  sequel_pg also offers a
  large (2-6x) performance increase over the default row fetching
  code that the Sequel postgres adapter uses.  In order to use it,
  you just need to install sequel_pg, and the postgres adapter will
  pick it up automatically.
  
* Mass assignment has been made about 10x faster by caching the
  allowed setter methods in the model.

= Other Improvements

* The following construct is now safe to use in environments that
  reload code without unloading existing constants:
  
    class MyModel < Sequel::Model(DB[:table])
    end
    
  Previously, this would raise a superclass mismatch TypeError.

* Sequel now handles the case where both an implicit and an explicit
  table alias are given to join_table, preferring the explicit alias.
  This can happen if you are using models with aliased table names
  and eager graphing them.  Previously, this would result in invalid
  SQL, with both aliases being used.

* You can use use an aliased table for the :join_table option
  of a many_to_many association.

* The active_model plugin now supports the final release of
  ActiveModel 3.0.0.
  
* Typecasting now works correctly for attributes loaded lazily
  when using the lazy_attributes plugin.
  
* The class_table_inheritance plugin now works with non-integer
  primary keys on SQLite.

* Temporary tables are now ignored when parsing the schema on
  PostgreSQL.

* On MySQL, an :auto_increment key with a true value is added to
  the Database#schema output hash if the related column is
  auto incrementing.

* The mysql adapter now handles Mysql::Error exceptions raised when
  disconnecting.

* On SQLite, emulated alter_table commands that require dropping
  the table now preserve the foreign key information, if SQLite
  foreign key support is enabled (it is by default).

* DSN-less connections now work correctly in more cases in the
  ODBC adapter.

* A workaround has been added for a bug in the Microsoft SQL
  Server JDBC Driver 3.0, involving it incorrectly returning a
  smallint instead of a char type for the IS_AUTOINCREMENT
  metadata value.

* An bug in the error handling when connecting to PostgreSQL using
  the do (DataObjects) adapter has been fixed.

= Backwards Compatibility

* The caching of allowed mass assignment methods can result in the
  incorrect exception class being raised if you manually undefine
  instance setter methods in the model class.  If you do this, you
  need to clear the setter methods cache manually:
  
    MyModel.clear_setter_methods_cache
