Let's get this finished

[George Russell]

Simon Marlow wrote:
> 
> > Is anybody actually depending on the old `CString'?  Or is
> > everybody using `PackedString' instead?
> 
> I don't believe anyone is using PackedString, except for Regex which
> arguably should be using CString instead.  I'd like to see a simpler
> PackedString which just corresponded to ByteArrays.
The current UniForM sources use both PackedString and CString in various
places.  The interface to PackedString happens to be documented, which was
why I thought it might be possible to rely on it.