3a8e10cb4f
Add CFMutableDictionary type. Added CFMutableDictionary that presents the mutable dictionary functions of CF. Tries to present a similar interface as CFDictionary. Fixes issue #93. <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/core-foundation-rs/135) <!-- Reviewable:end -->