[racket-dev] Release Announcement for v5.3

Below is a rough list of additions and changes for v5.3. If you
are responsible for a change, please either elaborate it into an
announcement item or tell me if it shouldn't be included in the
announcement. Let me know if I've missed something.

mflatt:
  - ffi/com, ffi/unsafe/com (ff41a896)
  - scribble xref change (a1fd742e)
  - "raco exe" can make launchers (2c479683)
  - prop:cpointer (6cd2e3c7)
  - handle-evt change to match doc (084278fa)
  - MysterX changes: ffi/com, removed ActiveX support (11de33d4)
  - openssl improvements (efcb6078, 1032ce8a)
  - submodules (3d69dfab)
  - racket/draw easier access to cairo (4f197f4b)
  - use AVL trees for immutable hashes (df0651c2)
  - (turon) add box-cas!, etc (868dcb6d)
  - libpng15/libpng12 (c5d3750d)
  - sgl/gl: NURBS (a55a20f9)
  - new error message convention
  - date/time stuff (ff8a062b, 4323096a)
  - changed module-name-resolver interface (c8f4ac6a)

robby:
  - grammar cycle check (93c21e34)
  - hole equality? (2afda360)
  - side-condition, define-judgment-form (b3c450ff)
  - -> contract optimizations (3f6a8355)
  - define-union-language (e4e4d70b)
  - plai changes (c42675f8)
  - add make-platform-bitmap (1945ff27)
  - define-extended-judgment-form (b7caf411)
  - drracket run 'main' submodule (72ec4070)
  - drracket easter egg tests (617df05e)
  - drracket run 'test' submodule (5c7a299c)
  - added context/path to contract errors (81252541)
  - added struct/dc, etc (5e03c7cf)
  - deprecate define-contract-struct (52fa588f)

eli:
  - regexp improvements (0eb5f09e)
  - json library (b35d1b01, 54021323)
  - xrepl improvements (89dee6f6)
  - add completions for zsh (904d2666)
  - doc search improvement (ecc43ff1)

james:
  - added would-be-future (a5676e9a)
  - added futures visualizer (b6f71ec4)

ryanc:
  - added db cursors
  - added statement cache
  - syntax/parse template (exp)
  - syntax/parse roles

asumu:
  - class/c changes (3eb963f6)
  - class contracts for racket/draw, racket/snip (30311058, 2e1d59f7)
  - add contracts to interfaces (6f4ad1de)
  - abstract methods (06091079)
  - generics (518bf0fd)
  - contracts for generics (552d6de9)
  - prompt/c, continuation-mark-key/c (de5c756d, 095d47fc)
  - mzlib deprecation notices (e4141077)

neil:
  - image, flomaps changes?
  - resizable plot snips (3ed1a787)

stamourv:
  - enable performance report for typed/racket/base (b73421f8)

tewk:
  - distributed places (09bed0d6)

samth:
   - keyword functions in TR (865a2cdc)
   - TR load time optimizations (794bfa50, 6bf14151)

matthias:
   - teaching lang doc reorg (5fbb660a)