How to get untyped CFDictionary?

[kvark]

io_surface::new gets the dictionary with default parameters, but the only way to create one appears to be with from_CFType_pairs that is strongly typed, and I don't see a way to get to untyped variant from here.

Related to #155

[jrmuizel]

io-surface 0.11 has a fixed io_surface::new() that takes a typed CFDictionary