[racket-dev] Release Announcement for v5.3.2

The release announcement sketch that I have so far is below.  Please
mail me new items and/or edits.
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mflatt:
  - generalized local-type tracking for unboxing (bdf1c3e1)
  - removed sirmail (3e505af4)
  - added file/untar (3a76581a), file/untgz (0f47069f), file/unzip 
(8a77d87a)
  - raco setup: use db for doc tags (8c1b5db8)
  - serialize: simplify quotable values (20bdbb6d)
  - f[xl]vectors: read/write (492167c2 with tewk, 9cf821b3) and 
serialize (9e8477dd)
  - faster FFI calls (42a03421)
  - support MinGW build (5b016b4c)
  - ffi/com: added com-get-property* (0f909af7)
  - added phantom byte strings (aa08a684)
  - added exn:fail:{filesystem,network}:errno (cdfc4912)

jay:
  - planet2 (fae660b0), versions for dependencies (0e140a81)

robby:
  - improvements to online check syntax (c6caf113)
  - added show-derivations to redex (9377b634)
  - improved language dialog (c02797b1)
  - deprecated mrlib/cache-image-snip (0b332a17)
  - sped up tab switching (4e95220d)

ntoronto:
  - math library (f2dc2027, 0936d8c2, 3670916a)
  - plot/typed (5a2aa226)

stamourv:
  - serialize srclocs (cc8bd4f2)
  - define-inline (b715a6fe)

ryanc:
  - ssl additions (d6cb2ece, f446adad, ba62b1dd)
  - ssl default CA certs (4b4113d5, 7b0a13bf, 10a34881)
  - db: start-transaction (05e7e61d), exn (30397acc), sql-bits (a2ae8137)
  - racket/lazy-require (fd7d8a41)

matthias:
  - batch-io updates (69800aa5)

eli:
  - DMG improvements (baa0e126, 48380b48)

bfetscher:
  - define-relation improvements (cf9b0f77)

jensaxel:
  - bit-vectors (028d14a8)

Joe Gibbs Politz:
  - added check-match to rackunit (e264e414)

Nadeem Abdul Hamid:
  - automatic paren mode improvements (8f3343cd)

J. Ian Johnson:
  - optimize singleton sequences (889f1591)

Greg Hendershott:
  - markdown rendering mode for Scribble (6aa6dc04)

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