Remove Setup.hs, use Setup.lhs only

[Neil Mitchell]

Hi

> In that sense, there's only one value (Custom), but defaultMain is
> common, and a reasonable number of packages use
>
>         main = defaultMainWithHooks defaultUserHooks
>
> I had a value for Distribution.Make.defaultMain too (but I don't know
> if anyone uses that).
>
> > Can't the Simple/Custom distinction be simply if the Setup.(l)hs is
> > present or not?
>
> If you have a field, cabal-setup can avoid compiling Setup.[l]hs in the
> common cases.

Another advantage of not having a Setup.hs file is that you can't get
your machine taken over just by installing a package. The library
author would have to be much more creative.

Thanks

Neil