New package suggestions (haskell, sml, xslide)

Ville Skyttä writes: I disagree about the packaging - while I would like to see support for haskell, I think this should be added to the prog-modes package. Creating more packages just adds confusion, IMO. Prog-modes becomes "support for various programming languages, except for <X> and <Y> and <Z> which have their own packages" - just more loose ends for users to keep track of. Furthermore, if a language is not supported in prog-modes it would be reasonable to assume that XEmacs does not have a mode to support that language. (Why do we have a prog-modes package at all? Why not just have a separate package for every language mode?) It's already true that some language modes have their own packages - e.g. ada and scheme - but I think that this is less than ideal. fortran has several files associated with it, but that doesn't mean it gets its own package.