• Added EXPERIMENTAL module Mojo::Util as a faster low level
  alternative to Mojo::ByteStream and rewrote many internals to use
  it instead.
  
• Improved Mojo::IOLoop performance by about 20%.
  
• Made automatic file storage upgrade smarter.
  
• Fixed overload stringification and improved overall performance by
  about 25%.
  
• Fixed start line/header buffering and improved performance by 8%.