md5 library now handles sha1

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

I've updated my MD5 library to handle sha1 because I found out that there
are several SHA1 libraries that use the same init/update/digest scheme and
that can be supported simply with a few #defines.

As usual, the library is available at
	http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/

Enjoy.
--lhf