- Port C++ SkeletonRenderer and RenderCommands to all runtimes
    - Will be used to snapshottesting via HeadlessTest, see also tests/
    - Can go into main package in all core runtimes, except for spine-libgdx, where it must go next to SkeletonSerializer in spine-libgdx-tests
- Generate language bindings in spine-c/codegen
    - Use CClassOrStruct, CEnum that get generated from spine-cpp-types.json and generate
        - Swift
        - Dart
- spine-c/codegen type extractor should also report typedefs like typedef long long PropertyId; so primitive type to some name, and we need to handle that in the codegen