= New Features

* Sequel::DEFAULT has been added a constant for the DEFAULT expression,
  useful in inserts and especially updates:

    DB[:a].where(:id=>1).update(:b=>Sequel::DEFAULT)
    # UPDATE "a" SET "b" = DEFAULT WHERE "id" = 1

* SQL::Function#filter for filtered aggregate functions is now
  supported on all databases.  On databases not supporting it natively
  (all except PostgreSQL 9.4+ and SQLite 3.30+), a CASE statement is
  used to emulate the support.

= Other Improvements

* NULLS FIRST/LAST is now used without emulation on SQLite 3.30+.

* The pg_enum extension now works correctly on PostgreSQL 8.3-9.0.

* Postgres::ArrayOp#join in the pg_array_ops extension now works
  correctly on PostgreSQL <9.1.