[plt-dev] Release Announcement for v4.2.1

The release announcement sketch that I have so far is below.  All
items except for Sam's are in, so send me edits and/or reorderings.

Note BTW, that a build is now on it's way, which solves (or "solves")
the planet-related problem.  (Sam: you're still on that nag list...)

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[Sam]
* typed-scheme stuff ("paths branch")

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* Faster installation of Planet packages that trigger install of
  other Planet packages, because the documentation index is
  updated only once after a group of packages is installed.

* The `syntax/parse' library provides macro writers with an
  enhanced syntax pattern matcher that reports errors based on the
  patterns' declared classes of syntax.

* Identifier mappings following the v4 dictionary interface and
  naming conventions are available from the `syntax/id-table'
  library.

* Redex: added `define-relation' and generalized patterns that
  appear in "where" clauses to use the full Redex pattern matcher.
  (This is a backwards incompatible change, but one often
  requested; see the Redex release notes for details.)

* The Web Server's serializable closures are now available for
  other purposes through the web-server/lang/serial-lambda
  library.

* Teachpacks: small changes to universe portion of the
  "universe.ss" API, plus the addition of a form for launching
  many (communicating) worlds simultaneously.  Bug fixes
  concerning conversion to strings.

* It is now possible to create custom scribble readers with a
  command characters different than `@', see
  `make-at-reader/inside' and `make-at-reader'

* Note: this is likely to be the last release that includes a
  solaris distribution.  If you need these builds, or if you have
  access to a (Sparc) Solaris machine than can be used in PLT
  builds, then please let me know.
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-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!
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