Hierarchy misspelt as Heirarchy

[jonsterling]

In a number of places in both this library and swift-LanguageServer, Hierarchy is misspelt as Heirarchy. I'm happy to fix it, but I first wanted to check how you wish to handle the breaking change. For example, the default implementation in ServerConnection could be deprecated and renamed, and there is a protocol RequestHandler in swift-LanguageServer with a method called prepareTypeHeirarchy which I could potentially mark @unavailable. But as this is a little subtle, I wanted to get your thoughts before proceeding. Let me know also if you prefer either to totally leave it alone.

[mattmassicotte]

Arg, I've made this kind of mistake a number of times. Thanks for reporting it.

I normally do go through the rename-and-deprecate process. But you are right that this is tricky with a protocol. My gut says to do something similar though. Add a new, correctly-spelled requirement, deprecate the old one, but also add an extension so the default implementation of the new calls the old.

I just did a little experimenting and I don't think this will be quite as smooth as other cases, but that's ok, as long as source compatibility doesn't break it can be fixed over time.