Add a default .hlint.yaml file, disabling all hints currently triggered

[ndmitchell]

Otherwise people might mistakenly try and send patches fixing them, e.g. #277. Also ensures they aren't shown in the IDE.

FWIW, the one that I would totally apply is:

src\HIE\Bios\Cradle.hs:637:26-53: Suggestion: Use catMaybes
Found:
  [comp | Just comp <- [mc]]
Perhaps:
  Data.Maybe.catMaybes [mc]

That seems much cleaner. Everything else has both pros and cons.