Refactoring set

Mostly review this commit: https://github.com/Haneke/HanekeSwift/commit/5fa7f30ddbc80598f05f48ec941e4c9ac863e265

The commits after that one are style changes. Sorry for mixing them in the same PR.
Yep. Haneke for Obj-C works like that as well. I might have to fix it there too.