libshift0, implementation of delimited control for C/C++

Copyright (c) 2011, Marek Materzok <tilk@tilk.eu>

1. About

  This library implements the shift0/reset0 delimited control operators,
  as introduced by Danvy in Filinski, and as used in my ICFP 2011 paper.

2. Caveats

  The continuations created by this library are not reentrant, i.e.
  one cannot call the continuation inside the call to the same continuation.

  The implementation is somewhat incompatible with stack-allocated
  objects with custom destructors in C++.

  The core operators are implemented in x86 assembly and don't work on
  other hardware architectures.

3. Copyright notice

   1. Redistributions of source code must retain the above copyright notice, 
      this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright 
      notice, this list of conditions and the following disclaimer in the 
      documentation and/or other materials provided with the distribution.
 
  The software is provided 'as is', without any warranty.