Fix haskell-show.el

[gracjan]

There is a file called haskell-show.el.

1. It is not referenced from any other file.
2. It is not documented in wiki, it is not documented in texi.
3. It depends on external program https://hackage.haskell.org/package/sexp-show that nobody has installed.
4. It depends on Read and Show instances being the derived versions.

In its current form it cannot be useful to people outside of very narrow group of enthusiasts that need better Show presentation.

What do we do with this?

[ivan-m]

Apparently sexp-show was downloaded 21 times in the last 30 days...

That said, I think it was one of @chrisdone's experiments that doesn't seem to have gone anywhere (since he no longer maintains it) so it's probably worth deleting.

[gracjan]

Those downloads might be due stackage building everything: https://www.stackage.org/package/sexp-show.

@ivan-m: Can you prepare a pull request cleaning this up?

[ivan-m]

Please ignore the first one; I made a typo and did a force-push to fix it.

[Hi-Angel]

Apparently sexp-show was downloaded 21 times in the last 30 days...

"9 downloads in the last 30 days" still. I'm really curious where these are coming from. Well, 1 of them was me just because I was trying to figure out what it does. But I only learned that invoking sexp-show --help hangs, as if it waits for something. But no clue who's still downloading this undocumented and for decade abandoned project.