Add missing tox.ini

tox.ini

+[tox]
+envlist = pep8,docstyle
+skipsdist = True
+
+[testenv:pep8]
+deps =
+    flake8
+basepython = python3
+commands =
+    flake8 {posargs}
+
+[testenv:docstyle]
+deps =
+    pydocstyle
+basepython = python3
+commands =
+    pydocstyle --verbose {posargs}
+
+[flake8]
+# W504 skipped because it is overeager and unnecessary
+ignore = W504
+show-source = True
+exclude = .git,.venv,.tox,dist,doc,*egg,build,venv
+import-order-style = pep8
+max-line-length = 80
+
+
+[pydocstyle]
+# D104 Missing docstring in public package
+# D203 1 blank line required before class docstring
+# D213 Multi-line docstring summary should start at the second line
+# D214 Section is over-indented
+# D215 Section underline is over-indented
+# D401 First line should be in imperative mood; try rephrasing
+# D405 Section name should be properly capitalized
+# D406 Section name should end with a newline
+# D407 Missing dashed underline after section
+# D408 Section underline should be in the line following the section’s name
+# D409 Section underline should match the length of its name
+# D410 Missing blank line after section
+# D411 Missing blank line before section
+ignore = D104,D203,D213,D214,D215,D401,D405,D406,D407,D408,D409,D410,D411
+match-dir = ^(?!\.tox|venv).*
+match = ^(?!setup).*\.py
+