= New Features

* A :qualify_tables option has been added to the
  class_table_inheritance plugin, which will automatically qualify
  subclass tables with the same qualifier as the superclass table
  if the superclass table is qualified.

* Model#save_validation_on_next_save! has been added, which skips all
  validation on the next save to the object, including the running
  of validation related hooks.  This method is designed for use only
  when Model#valid? is called on the object before saving, to avoid
  running validations on the object twice.  This method takes
  precedence even over an explicit validate: true option passed to
  Model#save, and as such should be used with care.

* The postgres adapter now supports a :conn_str Database option to
  use a PostgreSQL connection string (e.g. "host=foo port=2442") when
  connecting.  This option has preference over other connection
  related options if it is present.

= Other Improvements

* If a foreign key for a model object is changed from a nil value to
  a non-nil value, any cached associated objects related to the
  foreign key are no longer removed.  Such associated objects could
  only be set manually, and if they have been set manually, it is
  probably not a good idea to remove them automatically.

* When using the nested_attributes plugin, new *_to_many associated
  objects are not validated twice when saving.

* The default table alias when using the class_table_inheritance
  plugin now correctly handles qualified tables.

* A theoretical thread safety issue when assigning connections
  in the threaded connection pools has been fixed.

* Renaming columns is now supported without emulation when using
  SQLite 3.25+.
