new logos

[Luiz Henrique de Figueiredo <lhf@...>]

I've added 32x32 and 16x16 versions of the Lua logo, suitable for
using as icons in Windows or elsewhere:

 http://www.tecgraf.puc-rio.br/lua/images/
 http://csg.uwaterloo.ca/~lhf/lua/images

--lhf