Multiple python versions (#42)

* Support multiple Python versions in single build

* RPATH + Split up config into config and runtime

* pybind11 submodule

* Docker build updates

examples/python/pyproject.toml

@@ -0,0 +1,5 @@
+
+[tool.black]
+line-length = 80
+target-version = ['py38']
+include = '\.py'