* Improve TCFType macros
This adds the following new features:
* `declare_TCFType!`: Generics are accepted.
* `impl_TCFType!`: Non-defaulted generics are accepted, and impls are
fixed to be for all generics.
In addition, some warnings are silenced and the macros no longer depend
on any traits being in scope in the caller.
* Support generics in impl_CFComparison
* Add generic test for macros
Tyler Mandry
9d8c74ea34