[plt-scheme] New sandbox library

The sandbox library moved from the handin-server to mzlib, since it is
useful in a general context too.  It has also been extensively
improved.  The MzLib manual has a chapter that describes the new
library, and there is a test file (collects/tests/mzscheme/sandbox.ss)
with many examples of using it.

(Note that this is not a tool for writing test suits, but a very
convenient base for building testing tools, the test file demonstrates
this.)
-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!