When user disabled ghc-mod, haskell mode should fallback to interactive
mode, so type bindings (and some others) are working properly. It's also
useful for ghci-ng users, but doesn't affect ghci-ng-only bindings.
Fix#3777
By default `C-c C-l` shows following error:
```
haskell-mode-enable-process-minor-mode: Run ‘C-h f haskell-mode‘ for instruction how to setup a Haskell interaction mode.
```
Which might confuse users and they might end up setting
interactive-haskell-mode, which in most cases not what we want.
Also, it gives short key binding for emacs-only editing style users to
bring up REPL.
- fix some inaccuracies
- add more notes about using ghc-mod
- add more notes about using ghci-ng
- add more notes about using shm
- add more troubleshooting
- update section about setting up PATH by updating value of
=exec-path= (previously it was saying to update it in =user-init=
function, but looks like you need to do it in =user-config=) -
following #1718
- add FAQ section
- add note about setting up =stack-ghci= as =haskell-process= (as
noted in #2142)
- add note about fixing problems with =ghc-mod= and =stack=
- add note about fixing stuck REPL (following #3271)
Helm seems to treat "!" specially in pattern matching, so having a ! in
the pattern string when traversing directories is problematic. This
change fixes#2737, because as far as I can tell "+" has no special
meaning in a helm pattern.
Of course, we can choose a different character, but I'm fond of "+" as
representing "more layers here".
