= New Features

* A concurrent_eager_loading plugin has been added.  This plugin
  builds on top of the async_thread_pool Database extension and
  allows eager loading multiple associations concurrently in
  separate threads.  With this plugin, you can mark datasets for
  concurrent eager loading using eager_load_concurrently:

    Album.eager_load_concurrently.eager(:artist, :genre, :tracks).all

  Datasets that are marked for concurrent eager loading will use
  concurrent eager loading if they are eager loading more than one
  association.  If you would like to make concurrent eager loading
  the default, you can load the plugin with the :always option.

  All of the association types that ship with Sequel now support
  concurrent eager loading when using this plugin. For custom eager
  loaders using the :eager_loader association option, please see the
  documentation for the plugin for how to enable custom eager loading
  for them.

= Other Improvements

* The date_arithmetic extension now handles ActiveSupport::Duration
  values with weeks, as well as :weeks as a key in a hash value. Weeks
  are converted into 7 days internally.

* The shared SQLite adapter now emulates the dropping of non-composite
  unique constraints.  Non-composite unique constraints are now
  treated similarly to composite unique constraints, in that dropping
  any unique constraints on a table will drop all unique constraints
  on that table.