lint: detect incorrect indentation within createSanctuary

[davidchambers]

This is an alternative to #457. It adds more code, but may prove easier to maintain. I'm interested in your thoughts, @futpib.

[davidchambers]

@Avaq approved this pull request in a private message on Gitter.

[davidchambers]

I'm actually going to reject this pull request. I've realized that due to sanctuary-js/sanctuary-def#179 we'll soon need to disable the indent rule entirely. ESLint doesn't appreciate this formatting:

//    I :: a -> a
const I =
def ('I')
    ({})
    ([a, a])
    (I);