proptotype of make style dep stuff

[Marc Weber]

> I've also wondered if the command line UI could be completely separated,
> though that could make bootstrapping too hard.
You could distribute a "bootstrapping" version of cabal shipping with the command
line UI as hidden modules.
If you build cabal later on you could just shipt without the files for
the command line UI, then the external command line gui would be used.
Of course the local bootstrapping copy must be updated when the command
line gui lib is changed.
Not sure wether this makes much sense then.

Marc