tox: add envs to build sdist, pure/native wheels, and upload to pypi

tox.ini

@@ -55,3 +55,41 @@ deps = requests
 changedir = {toxinidir}
 commands =
     python tools/update_cython_shadow.py {posargs}
+
+[testenv:sdist]
+deps =
+    setuptools
+    cython
+changedir = {toxinidir}
+commands =
+    python -c 'import shutil; shutil.rmtree("dist", ignore_errors=True)'
+    python setup.py --with-cython sdist --dist-dir dist
+
+[testenv:pure-wheel]
+deps =
+    {[testenv:sdist]deps}
+    pip
+    wheel
+setenv = CU2QU_WITH_CYTHON=0
+changedir = {toxinidir}
+commands =
+    {[testenv:sdist]commands}
+    pip wheel --pre --no-deps --no-cache-dir --wheel-dir dist --find-links dist \
+        --no-binary {[tox]package_name} {[tox]package_name}
+
+[testenv:native-wheel]
+deps = {[testenv:pure-wheel]deps}
+setenv = CU2QU_WITH_CYTHON=1
+changedir = {toxinidir}
+commands = {[testenv:pure-wheel]commands}
+
+; we only upload the pure cu2qu-*-py2.py3-any.whl (for now)
+[testenv:pypi]
+deps =
+   {[testenv:pure-wheel]deps}
+   twine
+passenv = TWINE_USERNAME TWINE_PASSWORD
+changedir = {toxinidir}
+commands =
+    {[testenv:pure-wheel]commands}
+    twine upload dist/*.whl dist/*.zip