Updated to 7.0 deployment target & refactored deprecated methods.

I'm not sure if there's a hard and fast convention for using one over the other.  Some say yes, others say no.  My reasoning is this:

- It's defined in `MacTypes.h`, and has historically applied to more low-level development in OS X.
- Using the `nil` nomenclature for primitives squicks me out a little.  As a corollary, I think it reads as type-ambiguous due to the aforementioned mixing of reference type nomenclature in a value type enumeration.

That said, I don't feel strongly about it. :)