v1.2.0

• Feature: Support unwrapping object streams by buffering original write chunks in array.
  (#15 by @clue)

• Feature: Clean up unneeded references for unwrapped streams when closing.
  (#18 by @clue)

• Fix: Writing to closed unwrapped stream should return false (backpressure).
  (#17 by @clue)

• Improve test suite to support PHPUnit 7, PHP 7.3 and fix incomplete test
  and improve API documentation.
  (#16 and #19 by @clue)