• Enable extern type aliases to be passed and returned by value across the FFI as long as an unsafe impl ExternType impl claims that the underlying C++ type is trivially move constructible and trivially destructible; see https://docs.rs/cxx/0.5.0/cxx/trait.ExternType.html#associatedtype.Kind (#325, thanks @adetaylor)
• Expose a way for particular generic type instantiations of std::unique_ptr and std::vector, like UniquePtr<MyType>, to be produced on demand (#336)
• Enable import of handwritten as well as generated headers from direct dependencies in the Cargo-based workflow; see https://docs.rs/cxx-build/0.5.0/cxx_build/static.CFG.html#cfginclude_prefix (#346, #347)