= New Features

* A set_literalizer extension has been added, for treating Set
  instances in datasets similar to Array instances:

    DB.extension :set_literalizer
    DB[:table].where(column: Set.new([1, 2, 3]))
    # SELECT FROM table WHERE (column IN (1, 2, 3))

= Improvements

* Sequel now avoids the use of singleton classes for datasets on Ruby
  2.4+, instead creating a regular subclass whenever a dataset would
  be extended via #extension or #with_extend.  This significantly
  improves performance, up to 20-40% for common dataset usage,
  because it avoids creating new singleton classes for every dataset
  clone, and it allows for cached method lookup.

* Database#tables and #views now support a :qualify option on Microsoft
  SQL Server to returned qualified identifiers.

* The schema_dumper extension can now dump tables in non-default schemas
  when using Microsoft SQL Server.

* The schema_dumper extension now correctly dumps string column sizes
  when using Microsoft SQL Server.

= Backwards Compatibility

* Calling Sequel::Dataset.register_extension where the second argument
  is not a module now issues a deprecation warning.  Support for this
  will be removed in Sequel 6.
