The 'powered by Lua' logo (doc/powered-by-lua.gif ) is taken from:
http://www.lua.org/images .

Below is a copy of the copyright notice from the same web-page.

Stefano Trettel

===========================================================================
Copyright © 1998 Lua.org. Graphic design by Alexandre Nakonechnyj.

Permission is hereby granted, without written agreement and without license
or royalty fees, to use, copy, and distribute this logo for any purpose, 
including commercial applications, subject to the following conditions:

- The origin of this logo must not be misrepresented; you must not claim that
you drew the original logo.
- The only modification you can make is to adapt the orbiting text to your
product name.
- The logo can be used in any scale as long as the relative proportions of its
elements are maintained.
