gif.datatype contains LZW algorithm to decode GIF pictures during loading.
LZW algorithm was patented and maybe still is in some countries.
Only use this code, if you are sure, that you do not infringe a valid patent !
The encoding part (for saving) does not contain a LZW compressor, but produces
a GIF compatible result nevertheless, just a bit bigger.

Using GIF requires this statement in both technical and user documentation:
      "The Graphics Interchange Format(c) is the Copyright property of
      CompuServe Incorporated. GIF(sm) is a Service Mark property of
      CompuServe Incorporated."
