Release Announcement for Version 8.1

Racket v8.1

- DrRacket tabs can be dragged, and have new close buttons.

- Racket CS supports cross-compilation using `raco exe`.

- Racket CS supports Android on 32-bit and 64-bit ARM processors.

- The database library supports running queries in OS threads.

- Check-Syntax arrows correctly identify the definition site of
  identifiers with contracts.

- Racket CS performance has improved for structure predicates and

- Racket CS is faster at multiplying extremely large numbers and
  dividing large integers.

- Racket CS allows callbacks to raise exceptions if they are annotated
  with `#:callback-exns?`.

- New ephemeron hash tables simplify the implementation of tables where
  keys can refer to values.

- Typed Racket supports for/foldr.

- The stepper works for #lang htdp/*sl.

- Struct signatures work for the ASL teaching language.

The following people contributed to this release:

Alex Harsányi, Alex Knauth, Alexander Shopov, Alexis King, Andrew
Mauer-Oats, Anish Athalye, Ben Greenman, Bert De Ketelaere, Bob Burger,
Bogdan Popa, Brian Adkins, Cameron Moy, David Van Horn, Dexter Lagan,
Dominik Pantůček, Fred Fu, Greg Hendershott, Gustavo Massaccesi, Hazel
Levine, Ismael Luceno, Jack Firth, Jarhmander, John Clements, Jörgen
Brandt, Laurent Orseau, Lazerbeak12345, Matthew Flatt, Matthias
Felleisen, Micah Cantor, Mike Sperber, Noah Ma, Patrick McCarty, Paulo
Matos, Pavel Panchekha, Philip McGrath, Philippe Meunier, R. Kent
Dybvig, Robby Findler, Ryan Culpepper, Ryan Kramer, Sam Tobin-Hochstadt,
Sergiu Ivanov, Shu-Hung You, Sorawee Porncharoenwase, Stephen De
Gabrielle, William J. Bowman, bmitc, xxyzz, yjqww6, and ymdarake