Mark various turn-on-haskell-* functions obsolete

[ankhers]

This is still a work in progress, I just want some feedback on what I have done, and what I still need to do.

1. Does it make sense to convert turn-on-haskell-font-lock into a minor mode?
2. I'm not really sure what to do with turn-on-haskell-unicode-input-method. It honestly seems fine as it is.
3. I plan on converting turn-on-haskell-indent into a minor mode similar to haskell-indentation-mode.

Fix #771

[ankhers]

I'm not entirely sure why the tests are failing for my branch. I didn't touch the code that it is complaining about. Any insights would be great.

In toplevel form:
haskell-sort-imports.el:128:1:Error: the function `copy-list' is not known to be defined.
make: *** [haskell-sort-imports.elc] Error 1

[gracjan]

Tests are failing due to something else, do not worry about this.

Answers:

1. font-lock-mode is already an Emacs minor mode (enabled by default), so
   no need to do anything there.
   1a. turn-on-haskell-font-lock used to be used in ghc-mod (other package) so
   we need to keep it for a while as it is.
2. unicode input is good as it is, no need to change that one.
3. haskell-simple-indent won't be developed anymore, we should concentrate
   on haskell-indentation as that is where the future lies.

[gracjan]

I've fixed copy-list problem, just rebase over current master and you should be fine.

[ankhers]

I feel like that rebase didn't do what I wanted it to. Let me know if you want me to start a new branch for this.

[gracjan]

You should have just one commit on your branch. A clever use of git reset --hard, git cherry-pick and git push upstream +debt/mark_turn-on_functions_obsolete should do the trick.

[ankhers]

In that case, I think this is ready to be merged.

[gracjan]

@ankhers: Good stuff! Thanks!