gdbm binding updated

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

I've cleaned up my Lua binding for gdbm.
There still room for improvement, but I hope it's useful.

Following a suggestion by Steve Dekorte, I've also added a "proxy" method,
which allows a database to be accessed as if it were a table.
Just the kind of thing tag methods are designed for.

The code is available at
	ftp://ftp.tecgraf.puc-rio.br/pub/lhf/gdbm.tar.gz

(When lua-users.org is up, I'll move it there...)

Please send me your suggestions and comments.
Thanks.
--lhf