`use camel case` emits *two* hints

[MangoIV]

Currently hlint emits two hints for something like

mk_meth_spec_prags :: ....
mk_meth_spec_prags = ...

both on the type and the method itself. I think it should only emit one hint.

[ndmitchell]

That makes a lot of sense. I think the camel case hint should probably accumulate the hints it issues into a Map and never emit the same hint twice.