[PATCH]: added Converter, Encoder, Decoder, and Base64Converter

[Brian T. Rice]

Thanks. This (Encoder/Decoder code shape) is probably a good idea, and I had even been 
playing around with a Pipeline object type for managing multiple streams in a network, 
and this kind of fits with that generalization.

Waldemar Kornewald <wkornew at gmx.net> said:

> And this time I even attached the patch. :)
> 
> Waldemar Kornewald wrote:
> > Hi,
> > after having looked at Squeak again it seems they are not deriving
> > base64 from stream, but using a MIMEConverter framework. So, I did this
> > for Slate, too, but with a generic Converter, Encoder, Decoder.
> > Maybe one can build a media framework on top of this (*very*very*very*
> > simple system)? Making it MIME-specific did not make sense to me, at least.