It would be nice if pyrobuf distributed `pyrobuf_{list,util}.pxd` files in sys.path. This is needed in order to `cimport` `pyrobuf_list`. It seems, as documented in [Cython](https://cython.readthedocs.io/en/latest/src/userguide/source_files_and_compilation.html) documentation, it can be done with `package_data` parameter in `setup.py` file. As workaround, I have to keep the `pxd` files within repository of my own projects, which inconvenient to maintain.