updated md5 library

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

I've updated my MD5 library for Lua 5.0:
        http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/lmd5.tar.gz

I've added more information on MD5 libraries that may already be available in
Linux and Solaris; support for Plum's public domain implementation of Rivest's
library; a reset method; a polymorphic digest method that can also return
binary (=not printable hex) digests; and more tests.

Enjoy.
--lhf