GIF writer only; PNN quantizer excluded. Original LZW acknowledgements:
/*
  LZWEncoder.js
  Authors
  Kevin Weiner (original Java version - kweiner@fmsware.com)
  Thibault Imbert (AS3 version - bytearray.org)
  Johan Nordberg (JS version - code@johan-nordberg.com)
  Acknowledgements
  GIFCOMPR.C - GIF Image compression routines
  Lempel-Ziv compression based on 'compress'. GIF modifications by
  David Rowley (mgardi@watdcsu.waterloo.edu)
  GIF Image compression - modified 'compress'
  Based on: compress.c - File compression ala IEEE Computer, June 1984.
  By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
  Jim McKie (decvax!mcvax!jim)
  Steve Davies (decvax!vax135!petsd!peora!srd)
  Ken Turkowski (decvax!decwrl!turtlevax!ken)
  James A. Woods (decvax!ihnp4!ames!jaw)
  Joe Orost (decvax!vax135!petsd!joe)
  Matt DesLauriers (@mattdesl - V8/JS optimizations)
  Mathieu Henri (@p01 - JS optimization)
*/
