Added custom s.indexOf that takes into account element values.

Fixes s.remove.
Added S.of and S.from, and removed S.create.
Added element.toString.
Made s.length non-enumerable.
Made an s.length that works in all situations I could throw at it, unlike the previous one which failed until we call s.add at least once.
Started making s.filter work with plugins and selectors.
Added S.create, and made all the properties and methods on S non-enumerable, non-writable, and non-configurable.
Added the concept of hooks, which are events we fire off when shit happens, allowing plugins to do more complex crap.