No indentation cycling for case alternatives with haskell-indentation

[jstolarek]

Say I have:

foo = case undefined ofX

where X is the cursor position. Pressing Enter indents new line by two spaces:

foo = case undefined of
  X

That's not bad, but I think most haskell-mode's users over the years got used to behaviour of haskell-indent, which indented case alternatives relative to a case expression:

foo = case undefined of
        X

While the default behaviour might be disputable I would certainly expect that pressing Tab will cycle me between these two alternatives. Currently it doesn't, which I think should be fixed.