Pay dues to the compiler.
Publicize.
Rename the private ivar.
Unit is public.
Set conforms to CollectionType & ExtensibleCollectionType.
Merge branch 'master' into keeping-up-with-the-swiftses

Conflicts:
	Set/Set.swift
Merge pull request #6 from robrix/keeping-up-with-the-swiftses

Keeping up with the swiftses