Rename turn-on-haskell-* functions

[ankhers]

I noticed that turn-on-haskell-indentation has been marked obsolete in favour of haskell-indentation-mode. Are there plans to obsolete all turn-on-haskell-* in favour of haskell-*-mode?

I think it would ultimately be better to stick to a single naming convention.

[gracjan]

Yes. Consistency is important. If you do a pull request marking other functions as obsolete then we will be very grateful. Remember to change the documentation also.