Add support for UIPickerViews in Subliminal

UIPickerViews are under a different Window other than keyWindow, so I had to find the other one.  Otherwise it is pretty straightforward.  I'm leaning on the UIA methods a bit more heavily for interacting with the element, but open to suggestions.

Added one fairly comprehensive test case.
For Subliminal to build for 64-bit targets, we can't use "%d" or "%u"--instead, we should use:

* `"%lu", (unsigned long)foo` when `foo` is an `NSUInteger`, and
* `%li", (long)foo` when `foo` is an `NSInteger